重写shouldAutorateToInterfaceOrientation:，限制某个方向会改变原点的位置，原点会一直保持在左上角，但已经不是原来的左上角了

 

setStatusBarOrientation.改变状态栏的方向。它不会改变原点的位置，但会改变键盘的方向

旋转前self.myview的frame ={0,0,320,50}

CGAffineTransform at =CGAffineTransformMakeRotation(M_PI/2);

[self.myview setTransform:at];

旋转后frame={135,-135,50,320},视图的所有像素旋转90度

坐标是相对于父视图的

 

假如view已经转成竖的，这时通过设置frame而不是通过setTransform强制成横的话，会截掉部分图像

 

坐标多次变换的合成，要以被变换的view的局部坐标系为参照，比如

 

testView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 50)];
UILabel*label = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 100, 20)];
label.text =@"Test";
label.tag=100;
[testView addSubview:label];
此时的 frame ={0,0,320,50}

 

 


 
 
CGAffineTransform at =CGAffineTransformMakeRotation(M_PI/2);先顺时钟旋转90
at =CGAffineTransformTranslate(at,200,0);,
[self.testView setTransform:at]; 

Recently, I had need to provide a back button similar to the one used in Mobile Safari for a consulting project.

Many of the buttons used in the built-in iPhone applications are made available via the SDK with built in button types and graphics. Unfortunately, the back button is not one of these.

Because I needed to display the toolbar button from inside a static library which can not include images, I had to render the back arrow directly in code.

Since this was a bit time consuming, I thought I would share in hopes that it saves someone else a little bit of time.

- (CGContextRef)createContext
{
// create the bitmap context
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(nil,27,27,8,0,
colorSpace,kCGImageAlphaPremultipliedLast);
CFRelease(colorSpace);
return context;
}
- (CGImageRef)createBackArrowImageRef
{
CGContextRef context = [self createContext];
// set the fill color
CGColorRef fillColor = [[UIColor blackColor] CGColor];
CGContextSetFillColor(context, CGColorGetComponents(fillColor));
CGContextBeginPath(context);
CGContextMoveToPoint(context, 8.0f, 13.0f);
CGContextAddLineToPoint(context, 24.0f, 4.0f);
CGContextAddLineToPoint(context, 24.0f, 22.0f);
CGContextClosePath(context);
CGContextFillPath(context);
// convert the context into a CGImageRef
CGImageRef image = CGBitmapContextCreateImage(context);
CGContextRelease(context);
return image;
}
- (UIBarButtonItem *)backButton
{
CGImageRef theCGImage = [self createBackArrowImageRef];
UIImage *backImage = [[UIImage alloc] initWithCGImage:theCGImage];
CGImageRelease(theCGImage);
UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithImage:backImage
style:UIBarButtonItemStylePlain
target:self.webView
action:@selector(goBack)];
[backImage release], backImage = nil;
return [backButton autorelease];
}