1.
isKindOfClass: returns YES if the receiver is an instance of the specified class or an instance of any class that inherits from the specified class.

isMemberOfClass: returns YES if the receiver is an instance of the specified class.

Most of the time you want to use isKindOfClass: to ensure that your code also works with subclasses.

示例代码：NSArrayTest.h

NSArrayTest.m

运行结果：

2011-03-03 14:20:01.501 pList[1246:a0f] (

    one,

    two,

    three

)

如果查看/tmp/data.txt，能看到下面的内容：

即NSArray默认是以xml格式来序列化对象的.

如果你用来存放数据的类是自己定义的，并不是上面这些预置的对象，那么就要借助正式协议NSCoding来实现序列化和反序列化。

比如，我们有一个自己的类Sample.h

这里我们定义几个不同类型的属性，有字符串，有整数，有浮点数，还有一个可变长的数组对象

Sample.m

注意其中的：encodeWithCoder与initWithCoder，这是NSCoding协议中定义的二个方法，用来实现对象的编码与解码。其实现也不复杂，利用的是key-value的经典哈希结构。当然一般在编码中，对于key的名字字符串，建议用define以常量方式事先定义好，以避免开发人员字符串键入错误。

测试一下：

如果你要将代码中的某个部分标注起来，以便以后和方便的找它这部分代码，则我们可以使用书签。

选中一段文本或在源文件中放入插入点，然后选择Edit->Add to Bookmarks（快捷键 command + D),出现提示时输入书签名。

k)代码编辑器的导航条

导航条 就是在本文编辑窗口的顶部。

导航条上有个功能菜单，我们可以通过#pragma mark命令向 功能菜单上添加项。#pragma指令将objective-c将常规代码之外的信息或说明传递给编译器和代码器。通常，#pragma是被忽略，如果你的编译器不认识它就会忽略它，不会报考警告。

除了通过#pragma mark向功能菜单添加项；

在注释中以如下关键字符打头的文本都会被添加到功能菜单：

MARK:

TODO:

FIXME:

!!!:

???:

L)通过研究助手（Research Assistant）获取Xcode 的文档和参考资料。

可以通过Help->Show Research Assistant 打开研究助手；一旦研究助手的浮动窗口被打开后，浮动窗口中的内容会随着你与Xcode 交互操作的内容改变而改变。

如下图所示：

在Tire.m文件中，当光标在NSString类上时，研究助手浮动窗口所显示的信息：

切换到文件Tire.h中，研究助手的浮动窗口就显示有关NSObject的信息：

M)文档管理程序

我们可以通过访问苹果公司的官方API文档；方法是按住Option键并双击某个要查看的符号。如我们按住Option键并双击NSString符号将在文档浏览器窗口中打开有关NSString的资料信息，如下图：

按住control键并单击文档区域来打开pop菜单，选择任何菜单项，在另一个窗口中打开该文档。

M)如何调试程序？

（a）有两种方法：一是暴力调试，二是使用调试器调试。

什么是暴力调试？

暴力调试就是在你的程序中添加NSLog（）语言，将程序的控制流程和一些重要数据输出到终端上。

调试器调试：

调试器 就是介于你编写的应用程序和操作系统之间的一种程序，可以对你的程序进行控制，如停止，执行，单步跟踪等。

Xcode使用的调试器是GDB。

Xcode除了有GDB外，还有一个微型调试器，它是一个浮动窗口，通过它我们能接跳过GDB调试器做一些简单的调试工作。

Xcode有一个提供大量概述信息的调试窗口。

Xcode提供一个调试控制台，通过它可以直接向调试器发调试命令。

（b）如何用调试器进行调试？

         （1）编译程序时必须使用编译器的Debug配置，这样编译出的程序包含调试信息（调试器要用的信息）

         （2）调试时 需要让程序在调试器模式下运行。

                  在Xcode中有两种运行程序的方法：Run->run  (快捷键：command + R)， 不用调试器运行程序；

                                       Run->Go(Debug)或者Run->Debug(快捷键：command+Y)，使用调试器运行程序。

         （3）对 断点 的操作

            如何设置断点？

                   在 边列（gutter）上单击 就可以设置一个蓝色的断点；在次单击就disable该断点；如果要删除该断点                      就将该断点拖出边列。

             调试快捷键：

                  continue    :    option + command + P

                  step Into   :     shift + command + I

                  step Over :      shift + command + O

                  step Out   :      shift + command + T

            打开Xcode的调试窗口（点击调试控制栏上一个有喷雾器的方框）如下图：

         通过该窗口，可以执行各种调试命令并观察变量值的变化。

          如下是GDB的命令调试窗口，在其中可以输入gdb的调试命令对程序进行调试：

          通过调试控制栏上一个控件(黑色方框控件右边的那个),可以察看函数调用栈；如上图所示。

            [Note]边列(断点所在的列) 傍边较窄一列就是 焦点列。

到此为止，我们大概学习了Xcode这一强大的工具，要想深入研究它，我们还有很多的路要走，不过我们已经有了一个好的开始...

How to use iPhone with File I/O Functions: A Tutorial for Software Developers

Norman McEntire

Version 1.4 Sep 1. Thank you Freedy.

Version 1.3 Aug 6. Thank you Chris B.

Version 1.2 May 1. Thank you Pierre M.

Version 1.1 January 20

Copyright © 2009 Servin Corporation. http://servin.com

Introduction

The iPhone OS, like Mac OS X, provides both Apple specific file I/O functions, and Unix-type file I/O functions.

For example, you can use Apple specific functions to find the paths related to your application. You can also use Apple specific Object-C classes to read/write files.

An alternative is to use Unix-specific functions to read/write files. In addition to the standard open/close/read/write, you can do memory mapping, where the file is mapped directly into your address space.

In this Servin Mini-Course, you will learn how to use Apple-specific functions and class methods to perform file I/O.

iPhone Software Skills You Will Learn

• How to use Xcode to create a Window-Based App.
• How to display text output in a UITextView control.
• How to use NSBundle to find the resource path.
• How to use NSString to read a file.
• How to use NSSearchPathForDirectoriesInDomains() to find common search paths.

Prerequisites

• You should have already setup your iPhone software development environment. If this is not the case, then refer to the iPhone Flashlight App: Hands-On for Software Developers

Startup Xcode

If Xcode is not already running, start it up:

1. On the Mac Desktop, double-click on the Finder icon (the icon with the face on it).
2. On the left-side of the Finder window, click on Macintosh HD.
3. On the right-side of the Finder window, click on the Developer folder.
4. Click on the Applications folder.
5. Double-click on the Xcode icon.

At this point, you should see the Xcode menu at the top of your desktop.

Create New Xcode Project

With Xcode running, create a new Xcode project:

1. File > New Project.
2. On the left-side of the New Project window, select Application under iPhone OS.
3. On the right-side of the New Project window, select Window-Based Application.
4. Click on the Choose button.
5. Enter FileIo for the project name.
6. Click on Save button.

At this point, you should see Xcode open a new window that shows a number of files.

Build Default App

Go ahead and build the default application:

1. Click on the Build and Go button.
2. After a brief moment, you should see the code running in the iPhone Simulator.
3. Observe the status bar at the top of the window, and a white window everywhere else.
4. In the iPhone Simulator, press the Home button to stop the application.

Edit FileIoAppDelegate to Add UITextView as Subview to UIWindow

In this exercise, you will edit FileIoAppDelegate.h and FileIoAppDelegate.m to add a UITextView as a subview to the UIWindow.

1. In Xcode, in the Groups & Files window on the left-side, click on the Classes folder.
2. You should see the following files on the right-side of the window:

   FileIoAppDelegate.h
   FileIoAppDelegate.m
   

3. Select FileIoAppDelegate.h so that it appears in the Xcode editor window.
4. Edit the code to match the following:

   #import <UIKit/UIKit.h>
   
   @interface FileIoAppDelegate : NSObject <UIApplicationDelegate> {
   	UIWindow *window;
   
   	UITextView *textView;
   
   }
   @property (nonatomic, retain) IBOutlet UIWindow *window;
   
   @property (nonatomic, retain) UITextView *textView;
   
   @end
   

5. The above code adds a member variable named textView, which is a pointer to an object of type UITextView. Our goal is to use the UITextView control to display the output.
6. We will not use Interface Builder for this demo, so we did not add the IBOutlet to the code that we entered.
7. Select FileIoAppDelegate.m into the Xcode editor window.
8. Edit the code to match the following:

   #import <FileIoAppDelegate.h>
   
   @implementation FileIoAppDelegate
   
   @synthesize window;
   
   @synthesize textView;
   
   
   - (void)applicationDidFinishLaunching:(UIApplication *)application {
   
   	// Create instance of UITextView
   	self.textView = [[UITextView alloc] 
   			 initWithFrame:[[UIScreen mainScreen] applicationFrame]];
   
   	// Add text
   	self.textView.text = @"Output will go here...";
   
   	// Make non-editable
   	self.textView.editable = NO;
   
   	// Add as subview to window
   	[window addSubview:self.textView];
   
   	// Decrement our usage count
   	[self.textView release];
   
   	[window makeKeyAndVisible];
   }
   

9. Build and Go.
10. You should see your app running, with the text "Output will go here..." displayed in the window.
11. Press Home in iPhone Simulator to stop the application.

As a review, in this exercise you added code to the FileIoAppDelegate class to create a UITextView, setting it so that it cannot be edited. You also added text to the UITextView, and then added the UITextView to the subview of the window.

Create MyFile.txt

In this exercise, you will create a file named MyFile.txt as a sample text file that you will later read and display in the iPhone window.

1. In Xcode, in the Groups & Files window on the left-side, click on the Resources folder.
2. You should see the following frameworks:

   - Info.plist
   - MainWindow.xib
   

3. Control+click on the Resources folder.
4. Select Add from the popup menu.
5. Select New File.
6. In the New File window, on the left-side of the window, under the category Mac OS X, click on Other.
7. In the New File window, on the right-side of the window, click on Empty File.
8. Click on Next.
9. Name the file MyFile.txt.
10. Click on Finish.
11. Under the Resources folder, you should now have three files:

    - MainWindow.xib
    - Info.plist
    - MyFile.txt
    

12. Click on MyFile.txt to select it into the Xcode editor.
13. Enter the following into the file:

    This is a text file.
    The file will be displayed on the iPhone.
    That is all for now.
    

As a review, you created a text file named MyFile.txt in the Resources directory of your project.

NSHomeDirectory()

In this exercise, you will use the NSHomeDirectory() function to retrieve the path to the home directory of your application:

NSString *NSHomeDirectory(void);

An important point: the location of your home directory is different depending on whether you are running on the iPhone Simulator or on an actual device (iPhone or iPod Touch).

1. In Xcode, in the Groups & Files window on the left-side, click on the Classes folder.
2. You should see the following files:

   - FileIoAppDelegate.h
   - FileIoAppDelegate.m
   

3. Click on FileIoAppDelegate.m to select it into the Xcode editor.
4. Edit the code to match the following:

   #import <FileIoAppDelegate.h>
   
   @implementation FileIoAppDelegate
   
   @synthesize window;
   @synthesize textView;
   
   - (void)applicationDidFinishLaunching:(UIApplication *)application {
   
   	// Create instance of UITextView
   	self.textView = [[UITextView alloc] 
   			 initWithFrame:[[UIScreen mainScreen] applicationFrame]];
   
   	NSString *homeDir = NSHomeDirectory();
   
   	// Add text
   	self.textView.text = homeDir;
   
   
   	// Make non-editable
   	self.textView.editable = NO;
   
   	// Add as subview to window
   	[window addSubview:self.textView];
   
   	// Decrement our usage count
   	[self.textView release];
   
   	[window makeKeyAndVisible];
   }
   

5. Build and Go.
6. When your application runs, you should see a path similar to the following displayed on the screen (the value will change based on whether you are on the iPhone Simulator or the iPhone device):

   /Users/student/Library/Application Support/iPhone/Simulator/User/Applications/...
   
   - OR (on an actual device) -
   
   /var/mobile/Applications/...
   

As a review, in this exercise you used the NSHomeDirectory() function to find the pathname of your applications home directory.

NSTemporaryDirectory()

In this exercise, you will use the NSTemporaryDirectory() function to retrieve the path to the temporary directory for use by your application.

NSString *NSTemporaryDirectory(void);

An important point: the location of your temporary directory is different depending on whether you are running on the iPhone Simulator or on an actual device (iPhone or iPod Touch).

1. In Xcode, click on FileIoAppDelegate.m to select it into the Xcode editor.
2. Edit the code to match the following:

   #import <FileIoAppDelegate.h>
   
   @implementation FileIoAppDelegate
   
   @synthesize window;
   @synthesize textView;
   
   - (void)applicationDidFinishLaunching:(UIApplication *)application {
   
   	// Create instance of UITextView
   	self.textView = [[UITextView alloc] 
   			 initWithFrame:[[UIScreen mainScreen] applicationFrame]];
   
   	// Get home directory
   	NSString *homeDir = NSHomeDirectory();
   
   
   	// Get temporary directory
   	NSString *tempDir = NSTemporaryDirectory();
   
   	// Format output
   	NSString *s = 
   		[NSString stringWithFormat:@"homeDir:\n"
   						 @"%@\n"
   						 @"tempDir:\n"
   						 @"%@\n",
   						homeDir,
   						tempDir];		
   	// Add text
   	self.textView.text = s;
   
   
   	// Make non-editable
   	self.textView.editable = NO;
   
   	// Add as subview to window
   	[window addSubview:self.textView];
   
   	// Decrement our usage count
   	[self.textView release];
   
   	[window makeKeyAndVisible];
   }
   

3. Build and Go.
4. When your application runs, you should see output similar to the following (the values will change based on whether you are on the iPhone Simulator or the iPhone device):

   homeDir:
   /Users/student/Library/Application Support/iPhone/Simulator/User/Applications/...
   tempDir:
   /var/folders/7m/....
   
   - OR (on an actual device)
   /private/var/mobile/Applications/.../tmp
   

As a review, in this exercise you used the NSTemporaryDirectory() function.

NSSearchPathForDirectoriesInDomains()

In this exercise, you will use the NSSearchPathForDirectoriesInDomains() function to retrieve various paths:

NSArray *
NSSearchPathForDirectoriesInDomains(
	NSSearchPathDirectory directory, //NSDocumentDirectory or NSCachesDirectory
	NSSearchpathDomainMask domainMask, //NSUserDomainMask
	BOOL exppandTilde); // YES

An important point: Although a NSArray object is returned, you will only use the first array entry (index 0), which will contain an NSString.

1. In Xcode, click on FileIoAppDelegate.m to select it into the Xcode editor.
2. Edit the code to match the following:

   #import <FileIoAppDelegate.h>
   
   @implementation FileIoAppDelegate
   
   @synthesize window;
   @synthesize textView;
   
   - (void)applicationDidFinishLaunching:(UIApplication *)application {
   
   	// Create instance of UITextView
   	self.textView = [[UITextView alloc] 
   			 initWithFrame:[[UIScreen mainScreen] applicationFrame]];
   
   	// Get home directory
   	NSString *homeDir = NSHomeDirectory();
   
   	// Get temporary directory
   	NSString *tempDir = NSTemporaryDirectory();
   
   
   	// Get documents directory
   	NSArray *arrayPaths = 
   		NSSearchPathForDirectoriesInDomains(
   			NSDocumentDirectory,
   			NSUserDomainMask,
   			YES);
   
   	NSString *docDir = [arrayPaths objectAtIndex:0];
   
   	// Format output
   	NSString *s = 
   		[NSString stringWithFormat:@"homeDir:\n"
   						 @"%@\n"
   						 @"tempDir:\n"
   						 @"%@\n"
   						 @"docDir:\n"
   						 @"%@\n",
   						homeDir,
   						tempDir,
   						docDir];		
   
   	// Add text
   	self.textView.text = s;
   
   	// Make non-editable
   	self.textView.editable = NO;
   
   	// Add as subview to window
   	[window addSubview:self.textView];
   
   	// Decrement our usage count
   	[self.textView release];
   
   	[window makeKeyAndVisible];
   }
   

3. Build and Go.
4. When your application runs, you should see output similar to the following:

   homeDir:
   /Users/student/Library/Application Support/iPhone/Simulator/User/Applications/...
   tempDir:
   /var/folder/7m/....
   docDir:
   /Users/student/Library/Application Support/.../Documents
   

As a review, in this exercise you used the NSSearchPathForDirectoriesInDomain() function.

Using NSBundle and pathForResource:ofType:

In this exercise, you will use the NSBundle class to report the path to the applications resources. The applications resources are stored in the application bundle, and the path to this bundle can be found with the method pathForRecoure:ofType:.

1. In Xcode, click on FileIoAppDelegate.m to select it into the Xcode editor.
2. Edit the code to match the following:

   #import <FileIoAppDelegate.h>
   
   @implementation FileIoAppDelegate
   
   @synthesize window;
   @synthesize textView;
   
   - (void)applicationDidFinishLaunching:(UIApplication *)application {
   
   	// Create instance of UITextView
   	self.textView = [[UITextView alloc] 
   			 initWithFrame:[[UIScreen mainScreen] applicationFrame]];
   
   	// Get home directory
   	NSString *homeDir = NSHomeDirectory();
   
   	// Get temporary directory
   	NSString *tempDir = NSTemporaryDirectory();
   
   	// Get documents directory
   	NSArray *arrayPaths = 
   		NSSearchPathForDirectoriesInDomains(
   			NSDocumentDirectory,
   			NSUserDomainMask,
   			YES);
   
   	NSString *docDir = [arrayPaths objectAtIndex:0];
   
   
   	NSString *myFilePath = [[NSBundle mainBundle]
   				pathForResource:@"MyFile"
   				ofType:@"txt"];
   
   	// Format output
   	NSString *s = 
   		[NSString stringWithFormat:@"homeDir:\n"
   						 @"%@\n"
   						 @"tempDir:\n"
   						 @"%@\n"
   						 @"docDir:\n"
   						 @"%@\n"
   						 @"myFilePath:\n"
   						 @"%@\n",
   						homeDir,
   						tempDir,
   						docDir,
   						myFilePath];		
   
   	// Add text
   	self.textView.text = s;
   
   	// Make non-editable
   	self.textView.editable = NO;
   
   	// Add as subview to window
   	[window addSubview:self.textView];
   
   	// Decrement our usage count
   	[self.textView release];
   
   	[window makeKeyAndVisible];
   }
   

3. Build and Go.
4. When your application runs, you should see output similar to the following:

   homeDir:
   /Users/student/Library/Application Support/iPhone/Simulator/User/Applications/...
   tempDir:
   /var/folder/7m/....
   docDir:
   /Users/student/Library/Application Support.../Documents
   myFilePath:
   /Users/student/Library/Application Support/.../FileIo.App/MyFile.txt
   

As a review, in this exercise you used the NSBundle class to determine the path to the MyFile.txt, which is stored as part of the resource bundle.

Using NSString and stringWithContentsOfFile:encoding:error:

In this exercise, you will use the NSString class to read the MyText.txt file.

1. In Xcode, click on FileIoAppDelegate.m to select it into the Xcode editor.
2. Edit the code to match the following:

   #import <FileIoAppDelegate.h>
   
   @implementation FileIoAppDelegate
   
   @synthesize window;
   @synthesize textView;
   
   - (void)applicationDidFinishLaunching:(UIApplication *)application {
   
   	// Create instance of UITextView
   	self.textView = [[UITextView alloc] 
   			 initWithFrame:[[UIScreen mainScreen] applicationFrame]];
   
   	// Get home directory
   	NSString *homeDir = NSHomeDirectory();
   
   	// Get temporary directory
   	NSString *tempDir = NSTemporaryDirectory();
   
   	// Get documents directory
   	NSArray *arrayPaths = 
   		NSSearchPathForDirectoriesInDomains(
   			NSDocumentDirectory,
   			NSUserDomainMask,
   			YES);
   
   	NSString docDir = [arrayPaths objectAtIndex:0];
   
   	NSString *myFilePath = [[NSBundle mainBundle]
   				pathForResource:@"MyFile"
   				ofType:@"txt"];
   
   
   	NSString *myFileContents = [NSString stringWithContentsOfFile:myFilePath
   					     encoding:NSUTF8StringEncoding
   					     error:nil];
   
   	// Format output
   	NSString *s = 
   		[NSString stringWithFormat:@"homeDir:\n"
   						 @"%@\n"
   						 @"tempDir:\n"
   						 @"%@\n"
   						 @"docDir:\n"
   						 @"%@\n"
   						 @"myFilePath:\n"
   						 @"%@\n"
   						 @"Contents of file:\n"
   						 @"%@\n",
   						homeDir,
   						tempDir,
   						docDir,
   						myFilePath,
   						myFileContents];		
   
   	// Add text
   	self.textView.text = s;
   
   	// Make non-editable
   	self.textView.editable = NO;
   
   	// Add as subview to window
   	[window addSubview:self.textView];
   
   	// Decrement our usage count
   	[self.textView release];
   
   	[window makeKeyAndVisible];
   }
   

3. Build and Go.
4. When your application runs, you should see output similar to the following:

   homeDir:
   /Users/student/Library/Application Support/iPhone/Simulator/User/Applications/...
   tempDir:
   /var/folder/7m/....
   docDir:
   /Users/student/Library/Application Support/.../Documents
   myFilePath:
   /Users/student/Library/Application Support/.../FileIo.App/MyFile.txt
   Contents of file:
   This is a text file.
   This file will be displayed on the iPhone.
   That is all for now.
   

As a review, in this exercise you used the NSString class to read the contents of MyFile.txt.

Using NSString and writeFileTo:atomically:encoding:

In this exercise, you will use the NSString class to write a new file named NewText.txt.

1. In Xcode, click on FileIoAppDelegate.m to select it into the Xcode editor.
2. Edit the code to match the following:

   #import <FileIoAppDelegate.h>
   
   @implementation FileIoAppDelegate
   
   @synthesize window;
   @synthesize textView;
   
   - (void)applicationDidFinishLaunching:(UIApplication *)application {
   
   	// Create instance of UITextView
   	self.textView = [[UITextView alloc] 
   			 initWithFrame:[[UIScreen mainScreen] applicationFrame]];
   
   	// Get home directory
   	NSString *homeDir = NSHomeDirectory();
   
   	// Get temporary directory
   	NSString *tempDir = NSTemporaryDirectory();
   
   	// Get documents directory
   	NSArray *arrayPaths = 
   		NSSearchPathForDirectoriesInDomains(
   			NSDocumentDirectory,
   			NSUserDomainMask,
   			YES);
   
   	NSString docDir = [arrayPaths objectAtIndex:0];
   
   	NSString *myFilePath = [[NSBundle mainBundle]
   				pathForResource:@"MyFile"
   				ofType:@"txt"];
   
   	NSString *myFileContents = [NSString stringWithContentsOfFile:myFilePath
   					     encoding:NSUTF8StringEncoding
   					     error:nil];
   
   	// Format output
   	NSString *s = 
   		[NSString stringWithFormat:@"homeDir:\n"
   						 @"%@\n"
   						 @"tempDir:\n"
   						 @"%@\n"
   						 @"docDir:\n"
   						 @"%@\n"
   						 @"myFilePath:\n"
   						 @"%@\n"
   						 @"Contents of file:\n"
   						 @"%@\n",
   						homeDir,
   						tempDir,
   						docDir,
   						myFilePath,
   						myFileContents];		
   
   	// Create pathname to Documents directory
   	NSString *newFilePath = [docDir stringByAppendingString:@"/NewFile.txt"];
   
   	// Write string to file
   	[s writeToFile:newFilePath
   	   atomically:YES
   	   encoding:NSUTF8StringEncoding
   	   error:nil];
   
   	// Add text
   	self.textView.text = s;
   
   	// Make non-editable
   	self.textView.editable = NO;
   
   	// Add as subview to window
   	[window addSubview:self.textView];
   
   	// Decrement our usage count
   	[self.textView release];
   
   	[window makeKeyAndVisible];
   }
   

3. Build and Go.
4. When your application runs, it displays output on the iPhone screen, and also writes the output to the NewFile.txt file.
5. While the iPhone Simulator is still running, open up a terminal window, and cat (concatenate) out the contents of the file:

   $ cat /Users/student/Library/Application Support/.../Documents/NewFile.txt
   ...
   

As a review, in this exercise you used the NSString class to write the contents of a NSString MyFile.txt.

Skills Review

• Xcode
• Window-Based Application
• UITextView
• NSHomeDirectory()
• NSTemporaryDirectory()
• NSSearchPathForDirectoriesInDomains()
• NSBundle
• mainBundle
• pathForResource:ofType:
• NSString
• stringWithContentsOfFile:encoding:error:
• writeToFile:atomically:encoding:error:

How To Contact Author

Feel free to contact the author for any of the following:

• You have a question or comment about this mini-course.
• You need to hire Servin to help with your software development project.
• You need to hire Servin to give an on-site training course for your software development team.

Updated 2009 Sep 1
Content viewable on all web browsers, including smart mobile phone devices.
Copyright © 1995-2009 Servin Corporation. All rights reserved.

1.将一个指定的图形放大或缩小为指定的尺寸，可以试试以下代码

-(UIImage*)scaleToSize:(UIImage*)img size:(CGSize)size  

{  

    // 创建一个bitmap的context  

    // 并把它设置成为当前正在使用的context  

    UIGraphicsBeginImageContext(size);  

    // 绘制改变大小的图片  

    [img drawInRect:CGRectMake(0, 0, size.width, size.height)];  

    // 从当前context中创建一个改变大小后的图片  

    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();  

    // 使当前的context出堆栈  

    UIGraphicsEndImageContext();  

    // 返回新的改变大小后的图片  

    return scaledImage;  

}

2.图片如何存入 iPhone 本地 Documents 的方法

在 UIButton 的 saveImage 方法里添加一张图片，以下代码可将图片存入本地的 Documents 下:

-(void)saveImage

{

    NSANSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);

    NSString *documentsDirectory = [paths objectAtIndex:0];

    NSString *savedImagePath = [documentsDirectory stringByAppendingPathComponent:@"savedImage.png"];

    //also be .jpg or another

    UIImage *image = imageView.image; // imageView is your image

    // Returns the data for the specified image in JPEG/PNG format.

    NSData *imageData = UIImagePNGRepresentation(image);    //UIImageJPEGRepresentation(image)

    [imageData writeToFile:savedImagePath atomically:NO];  

}

3. UIImageWriteToSavedPhotosAlbum保存图片的方法

用UIImageWriteToSavedPhotosAlbum往照片库里面存图片时，经常发生缩略图能看到但原图消失的问题

用 UIImageWriteToSavedPhotosAlbum(imageSave, nil, nil, nil), imageSave是UIImage类型，这样就保存进去了。

而且注意图片不宜过大，以免程序崩溃

4.保存已选取的图片，下次启动App时直接显示的方

如果您想在iPhone App里实现保存一张图片，下次再启动该App时直接自动显示该图的功能，可以使用以下方法

NSData *imageData = UIImageJPEGRepresentation(image, 1.0);

[NSData writeToFile: imagePath atomically:YES];

保存起来，启动时再读出就OK了

UIImage *_image = [[UIImage alloc]initWithContentsOfFile: imagePath];

5.在以图片为背景的view上直接写文字

-(void)drawAtPoint:(CGPoint)point withFont:(UIFont*)font orientation:(WBOrientation)orient;

-(CGPoint)drawInRect:(CGRect)rect withFont:(UIFont*)font orientation:(WBOrientation)orient alignment:(UITextAlignment)align;

UIFont * font = [UIFont fontWithName:@"Arial" size:18];  

NSString *str = @"Hello World";

[str  drawAtPoint:CGPointMake(0,70) withFont:font];

6.从 iPhone/iPad 图片库中读取图片的代码

如果您的App涉及到从iPhone/iPad图片库读取图片，不妨看看CocoaChina版主“angellixf”分享的代码，会为您节省很多时间。

UIImagePickerController * picker = [[UIImagePickerController alloc] init];

picker.delegate = self;

picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

[self presentModalViewController:picker animated:YES];

UIImagePickerControllerSourceTypePhotoLibrary,// 相片库

UIImagePickerControllerSourceTypeCamera//相机获取图片

UIImagePickerControllerSourceTypeSavedPhotosAlbum// 这个是自定义库，是由用户截图或保存到里面的

将图片保存到相片库的代码：

UIImageWriteToSavedPhotosAlbum(Image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);

MySingleton.h:

#import <Foundation/Foundation.h>
 
@interface MySingleton : NSObject {
 
}
+(MySingleton*)sharedMySingleton;
-(void)sayHello;
@end

MySingleton.m:

@implementation MySingleton
static MySingleton* _sharedMySingleton = nil;
 
+(MySingleton*)sharedMySingleton
{
@synchronized([MySingleton class])
{
if (!_sharedMySingleton)
[[self alloc] init];
 
return _sharedMySingleton;
}
 
return nil;
}
 
+(id)alloc
{
@synchronized([MySingleton class])
{
NSAssert(_sharedMySingleton == nil, @"Attempted to allocate a second instance of a singleton.");
_sharedMySingleton = [super alloc];
return _sharedMySingleton;
}
 
return nil;
}
 
-(id)init {
self = [super init];
if (self != nil) {
// initialize stuff here
}
 
return self;
}
 
-(void)sayHello {
NSLog(@"Hello World!");
}
@end

1.获得资源文件路径:

//- (NSString *)pathForResource:(NSString *)name ofType:(NSString *)extension

NSString *path=[[NSBundle mainBundle] pathForResource:@"bk" ofType:@"png"];

2.得到应用程序代理:

[[UIApplication sharedApplication] delegate];

3.应用程序大小:

[[UIScreen mainScreen] applicationFrame];

重要属性:

view

title

interfaceOrientation

tabBarController

tabBarItem

navigationController

navigationItem

parentViewController

重要方法:

viewDidLoad

viewDidUnload

viewWillAppear

viewWIllDisappear

presentModalViewController

dismissModalViewController

initWithNibName

2.UITabBarItem:

重要方法:

- (id)initWithTabBarSystemItem:(UITabBarSystemItem)systemItem tag:(NSInteger)tag

- (id)initWithTitle:(NSString *)title image:(UIImage *)image tag:(NSInteger)tag

3. UITabBarController:

重要属性:

delegate

viewControllers

selectedIndex

selectedViewController

重要方法:

setViewControllers

代理:

UITabBarControllerDelegate:

tabBarController:didSelectViewController:

tabBarController:shouldSelectViewController:

4. UINavigationController

重要属性:

delegate

navigationBar

viewControllers

topViewController

visibleViewController

重要方法:

initWithRootViewController

pushViewController

popViewController

popToViewController

popToRootViewController

setViewControllers

代理:

UINavigationControllerDelegate:

navigationController:didShowViewController:animated:

#pragma mark Table view methods

//有多少个分区

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView

{

    return 1;

}

// Customize the number of rows in the table view.   每一个分区有多少行. section为分区编号

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

{

    return 0;

}

// Customize the appearance of table view cells.  当要显示每一行时被调用.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 

{

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {

        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];

    }

    // Configure the cell.

    return cell;

}

// Override to support row selection in the table view.           当有一行被选中时被调用.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 

{

    // Navigation logic may go here -- for example, create and push another view controller.

    // AnotherViewController *anotherViewController = [[AnotherViewController alloc] initWithNibName:@"AnotherView" bundle:nil];

    // [self.navigationController pushViewController:anotherViewController animated:YES];

    // [anotherViewController release];

}

  [UIView beginAnimations:@"animationID" context:nil];

  [UIView setAnimationDuration:0.5f];

  [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];

       [UIView setAnimationTransition: UIViewAnimationTransitionFlipFromLeft forView:self.view cache:YES];

         //UIViewAnimationTransitionFlipFromLeft,

    //UIViewAnimationTransitionFlipFromRight,

    //UIViewAnimationTransitionCurlUp,

    //UIViewAnimationTransitionCurlDown,

       //要执行的动作.

       [UIView commitAnimations];

2.使用CATransition对象来实现: //公开的API

    CATransition *animation = [CATransition animation];

    animation.duration = 0.5f;

    animation.timingFunction = UIViewAnimationCurveEaseInOut;

    animation.fillMode = kCAFillModeForwards;

    animation.type = kCATransitionPush;//kCATransitionMoveIn kCATransitionReveal kCATransitionFade

    animation.subtype = kCATransitionFromLeft;//kCATransitionFromRight kCATransitionFromTop  kCATransitionFromBottom

     [self.view.layer addAnimation:animation forKey:@"animation"];

3.2.使用CATransition对象来实现: //末公开的API

    CATransition *animation = [CATransition animation];

//1.初始化:

//使用时需要一个图控制器来做为UINavigationController根视视图控制器,本例中为TestViewController:

UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:[[TestViewController alloc] init]];

[window addSubview:nav.view];

#define COOKBOOK_PURPLE_COLOR [UIColor colorWithRed:0.20392f green:0.19607f blue:0.61176f alpha:1.0f]

#define BARBUTTON(TITLE, SELECTOR) [[[UIBarButtonItem alloc] initWithTitle:TITLE style:UIBarButtonItemStylePlain target:self action:SELECTOR] autorelease]

//若一个视图控制器在栈中,则可以调用navigationController和navigationItem来获得导航控制器或项目

//2.在TestViewController的viewDidLoad函数中,可以对导航条属性进行设置:

self.navigationController.navigationBar.tintColor =  COOKBOOK_PURPLE_COLOR;

self.navigationItem.rightBarButtonItem =  BARBUTTON(@"Flip", @selector(flip:));

// Set up the segmented control for picking the animation direction

UISegmentedControl *seg = [[[UISegmentedControl alloc] initWithItems:[@"Left Right" componentsSeparatedByString:@" "]] autorelease];

seg.selectedSegmentIndex = 0;

seg.segmentedControlStyle = UISegmentedControlStyleBar;

self.navigationItem.titleView = seg;

@protocol  TestShow; 

@interface MyClass : NSObject<NSCopying>//遵守NSCopying协议

{

  id<TestShow> delegate;

}

@property (nonatomic,retain) id<TestShow> delegate;

@end

//自定义代理

@protocol TestShow

-(void)show;

@end

2.MyClass类的实现:

    重要属性:

    frame

    layer

    subviews

    tag

    superview

    userInteractionEnabled

    multipleTouchEnabled

    center

    重要方法

    initWithFrame:

    addSubview:

    insertSubview:atIndex:

    insertSubview:aboveSubview:

    insertSubview:belowSubview:

    exchangeSubviewAtIndex:withSubviewAtIndex:

    drawRect:

    viewWithTag:

    removeFromSuperview

2.UIScrollView使用实践:

    重要的属性:

    contentSize

    maximumZo

绘图前设置:

CGContextSetRGBFillColor/CGContextSetFillColorWithColor          //填充色

CGContextSetRGBStrokeColor/CGContextSetStrokeColorWithColor           //笔颜色

CGContextSetLineWidth                           //线宽度

绘图后设置:

注:  画完图后,必须

先用CGContextStrokePath来描线,即形状

后用CGContextFillPath来填充形状内的颜色.

2.常见图形绘制:

CGContextFillRect/CGContextFillRects

CGContextFillEllipseInRect

CGContextAddRect/CGContextAddRects

CGContextAddEllipseInRect

CGContextAddLines

CGContextMoveToPoint

CGContextAddLineToPoint

3.常见控制方法:

CGContextSaveGState

CGContextRestoreGState

4.创建内存图像context:

CGBitmapContextCreate       <-----CGContextRlease释放

CGColorSpaceCreateWithName    (KCGColorSpaceGenericRGB)

CGColorSpaceRlease

CGBitmapContextCreateImage()   <-----CGImageRlease 释放.

eg:

CGContextRef MyCreateBitmapContext (int pixelsWide,int pixelsHigh)

{

CGContextRef    context = NULL;

CGColorSpaceRef colorSpace;

void *          bitmapData;

int             bitmapByteCount;

int             bitmapBytesPerRow;

bitmapBytesPerRow   = (pixelsWide * 4);

bitmapByteCount     = (bitmapBytesPerRow * pixelsHigh);

colorSpace = CGColorSpaceCreateDeviceRGB();

bitmapData = malloc( bitmapByteCount );

if (bitmapData == NULL)

{

fprintf (stderr, "Memory not allocated!");

return NULL;

}

context = CGBitmapContextCreate (bitmapData,     pixelsWide,     pixelsHigh,     8,     bitmapBytesPerRow,     colorSpace,     kCGImageAlphaPremultipliedLast);

if (context== NULL)

{

free (bitmapData);

fprintf (stderr, "Context not created!");

return NULL;

}

CGColorSpaceRelease( colorSpace );

return context;

}

5.图形的变换:

CGContextTranslateCTM

CGContextRotateCTM

CGContextScaleCTM

   6.常用函数:

   CGRectContainsPoint();

CGRectContainsRect();

CGRectIntersectsRect();

CGRectIntersection();

CGPointEqualToPoint();

CGSizeEqualToSize();

  7.从原图片中取小图.

CGImageCreateWithImageInRect

8.屏幕快照:

#import "QuartzCore/QuartzCore.h"

UIGraphicsBeginImageContext(yourView.frame.size); 
[[yourView layer] renderInContext:UIGraphicsGetCurrentContext()]; 
UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext(); 
UIGraphicsEndImageContext(); 

1.设置实例变量值的方法通常称为设置函数setter,而用于检索实例变量值的方法叫做获取函数getter.getter一般为变量名,而setter一般为set+变量名(第一个字母大写).

2.合成存取器方法: 在接口定义部分使用@property指令标识属性,然后在实现部分使用@synthesize指令即可.

 eg:      @property int sum;

        @synthesize sum;

3.创建方法名时,参数名实际上是可选的.如

-(int) set: (int)n :(int) d;

这个方法名为: set::,要调用这个方法如下:

[ aFraction set:1 :3];

4.静态变量声明仍为static关键字修饰,如:static int hiCount=0;

5.有一个名为new的方法可以将alloc和init的操作结合起来.

eg:       Fraction *myFraction = [Fraction new];

6.id类型可以存任何的对象,而且对于返回值和参数类型来说,id是默认的类型,如下声名了一个返回为id类型的方法.

eg:                        -allocInit;

7.承继时方法的调用:首先检查该对象所属的类,如果有指定名称的方法,则调用它,如果没有,就检查它的父类,父类有时则调用,否则继续向上寻找.

8.分类(category)机制允许你以模块方式向现有类定义添加新方法,也就是,不必经常给同一接口和实现文件增加新定义.

eg:         @interface Fraction (MathOps)

//fun declaration...

    @end

    @implementation Fraction (MathOps)

//fun implement...

    @end

9.@class 类名,为向前声名.

10.编译时检查和运行时检查:

在给指定类型对象发送消息时,为编译时检查.

而给id类型对象发送消息时,为运行时检查.

11.RTTI:

  1.获得类对象:   [Square class]

    eg:如查看obj1与obj2是不是相同的类的实例.

  if([obj1 class] == [obj2 class] ) ...

  2.查看变量是不是不Fraction类的实例:

          [myFraction isMemberOf: [Fraction class]];

  3.要查看实例是否响应指定方法:

  [myFraction instancesRespondToSelector: @selector(setTo:over:)];

12.如果类包含多个初始化的方法,其中一个就应该是指定的(designated)初始化方法,并且其它所有初始化方法都使用这个初始化方法.

13.协议:多个类共享的一个方法列表,协议中列出的方法没有相应的实现.

eg:       @protocol NSCopying

-(id) copyWithZone:(NSZone *)zone;

@end

注意:协议是无类的,它不引用任何类.

14.预处理程序:

   1.   #define   与C语言的相同.

   2. 条件编译:

eg:                              #ifdef   

           ...

                                     #else

       ...  

                                     #endif

15.语言的基本特性:

  1.数组初始化不同之处:

  可以通过将元素编号放在一对大括号中可以以任意顺序初始化指定的数组元素.

eg:         int x=1233;

  int a[]={ [9]=x+1, [2]=3, [1]=2, [0]=1};

16.使用Foundation提供的数组,集合时,它们只能存放对象,所以不能将基本类型数据存放其中.要存放任意基本类型,可以使用NSNumber类根据这些数据类型来创建对象.

eg:       NSNumber类方法:

+(NSNumber*)numberWithInteger:(int) value;           

numberWithFloat;

numberWithLong;

numberWithChar;

integerValue longValue floatValue doubleVaue charValue

一般来说,你负责对此类的检索,如果在NSNumber对象中存储了一个值,那么也要用一致的方式进行检索.

17.对于NSArray.类方法arrayWithObjects:可以用来创建使用一列对象作为元素的数组,必须把该列表的最后一个值指定为nil,它实际上并不存在数组中.

要使用数组索引数来检索其中一个元素,用objectAtIndex:方法.

    18.各种容器类如:NSArray,NSDictionary,NSSet等,会将引入的元素的引用计数值来加1来获得所有权,而元素被移除时或者整个窗口对象被释放时,释放容器内所有权.

19.快速枚举数组或集合中的对象:

eg:                        for (AddressCard *theCard in book) 

//op theCard...

20.复制对象:

Foundation类提供了名为copy和mutableCopy方法,可以使用这些方法创建对象的副本.

注意:产生一个对象的可变副本并不要求被复制对象本身是可变的.这种情况同样适用于不可变副本,可以创建可变对象的不可变副本.

    使用copy或mutableCopy方法创建的对象采用的是浅复制,它意味着使用mutableCopy方法复制数组时,在内存中为新的数组对象分配了空间.并且单个元素复制到新数组中.

    要使自己的类支持copy方法,则自己的类必须尊守<NSCopying>协议. 实现 copyWithZone:方法来响应copy消息.

Logging

Display Images

Application Frame

Web view

Display the Network Activity Status Indicator

Animation: Series of images

Animation: Move an object

#define SCREEN_WIDTH [UIScreen mainScreen].bounds.size.width

#define SCREEN_HEIGHT [UIScreen mainScreen].bounds.size.height

    UIView* view1 = [[UIView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH/2, SCREEN_HEIGHT/2)];

    UIView* view2 = [[UIView alloc] initWithFrame:CGRectMake(SCREEN_WIDTH/2, 0, SCREEN_WIDTH/2, SCREEN_HEIGHT/2)];

    UIView* view3 = [[UIView alloc] initWithFrame:CGRectMake(0, SCREEN_HEIGHT/2, SCREEN_WIDTH/2, SCREEN_HEIGHT/2)];

    UIView* view4 = [[UIView alloc] initWithFrame:CGRectMake(SCREEN_WIDTH/2, SCREEN_HEIGHT/2, SCREEN_WIDTH/2, SCREEN_HEIGHT/2)];

    view1.backgroundColor = [UIColor redColor];

    [self.view addSubview:view1];

    view2.backgroundColor = [UIColor greenColor];

    [self.view addSubview:view2];

    view3.backgroundColor = [UIColor blueColor];

    [self.view addSubview:view3];

    view4.backgroundColor = [UIColor yellowColor];

    [self.view addSubview:view4];

注:
   1.实例方法:  方法前面的“-”是实例方法(类似于C++中的类成员函数)。
   2.类方法:    前缀为“+”的是类方法(类似于C++中的静态成员函数，或者是全局函数)
   3.类变量:    与C/C++语言中的静态变量一样，Objective-C 中的类变量就是以 static 声明的变量。(只在当前定义文件中有效)
   4.如果子类也想参照父类中的类变量的时候，须定义属性参照方法(类方法)。(这与面向对象中的封装概念有所背驰，降低了凝聚度)

类设计小结:

1. 头文件依然是.h,但实现文件从 .cpp变成了.m.
2. #import代替了#include，#import保证只会引用一次，相当于.h里的#ifndef #define #endif模式
3. 用@interface … @end来声明类，取代class ClassName{}
4. 用@implementation … @end来实现类

5. Data Members放在@interface ClassName : Parent{ … }中，默认权限为@protected，在ObjC里称为Instance Variables
6. Member Functions放在@interface ClassName: Parent{} … @end中，在ObjC里称为Instance Methods
7. Instance Methods的声明方式为：scope (returnType) methodName: (parameter1Type) parameter1Name;

8. scope分instance和class两种，分别用-和+表示

9. 调用method的方式是[Object  method]，相当于Object-> method()
10. 带参数调用method的方式是[Object method: parameter]

11. 没有Object，只有Pointer to Object
12. 通常的构造方式： Object * obj = [[Object alloc] init]
13. 析构的方式：[obj release]

14.多参数method的声明方式： scope (returnType) methodName: (parameter1Type) parameter1Name label1Name: (parameter2Type) parameter2Name … ;
15. labelName不是必须的

16. 这种特别的语法源自SmallTalk
17. private: [list of vars]     protected: [list of vars]    public: [list of vars] 改成了@private, @protected, @public

18. Class Variable用static的方法实现.
19. +(void) initialize 会在构造的时候被调用
20. ObjC通常用@符号表示语言的衍生部分

22. ObjC用id来表示范型对象的指针
23. 支持动态类型识别,即RTTI.

24. Categories机制可用于不继承已有class的前提下加入新功能
25. Posing机制允许Child取代Parent
26. Protocol相当于pure virtual class

27. ObjC由两种内存管理的方法，1) retain and release，2) retain and release/autorelease
28. Foundation相当于STL，NSArray对应vector，NSDictionary对应map
29. ObjC不支持Namespace
30. 不支持重载