示例代码：NSArrayTest.h
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#import <Foundation/Foundation.h>
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#define FILE_NAME @"/tmp/data.txt"
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@interface NSArrayTest : NSObject {
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NSArrayTest.m
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#import "NSArrayTest.h"
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@implementation NSArrayTest
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NSArray *arr = [NSArray arrayWithObjects:@"one",@"two",@"three",nil];//注:最后一个要以nil结尾
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[arr writeToFile:FILE_NAME atomically:YES];//(序列化为xml格式后)保存文件
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NSArray *arr2 = [NSArray arrayWithContentsOfFile:FILE_NAME];//read file
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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：
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<?xml version="1.0" encoding="UTF-8"?>
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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
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#import <Foundation/Foundation.h>
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@interface Sample : NSObject<NSCoding> {
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NSMutableArray *subThingies;
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@property(copy) NSString* name;
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@property int magicNumber;
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@property float shoeSize;
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@property (retain) NSMutableArray *subThingies;
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-(id) initWithName:(NSString *)n magicNumber:(int)m shoeSize:(float) ss;
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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
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@implementation Sample
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@synthesize magicNumber;
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@synthesize subThingies;
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-(id) initWithName:(NSString *)n magicNumber:(int)m shoeSize:(float)ss
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if (self=[super init])
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self.subThingies = [NSMutableArray array];
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[subThingies release];
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-(void) encodeWithCoder:(NSCoder *)aCoder
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[aCoder encodeObject:name forKey:@"name"];
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[aCoder encodeInt:magicNumber forKey:@"magicNumber"];
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[aCoder encodeFloat:shoeSize forKey:@"shoeSize"];
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[aCoder encodeObject:subThingies forKey:@"subThingies"];
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-(id) initWithCoder:(NSCoder *)aDecoder
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if (self=[super init])
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self.name = [aDecoder decodeObjectForKey:@"name"];
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self.magicNumber = [aDecoder decodeIntForKey:@"magicNumber"];
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self.shoeSize = [aDecoder decodeFloatForKey:@"shoeSize"];
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self.subThingies = [aDecoder decodeObjectForKey:@"subThingies"];
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-(NSString*) description
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NSString *description = [NSString stringWithFormat:@"%@:%d/%.1f %@",name,magicNumber,shoeSize,subThingies];
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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：
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#import <Foundation/Foundation.h>
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int main (int argc, const char * argv[]) {
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NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
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Sample *s1 = [[Sample alloc] initWithName:@"thing1" magicNumber:42 shoeSize:10.5];
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[s1.subThingies addObject:@"1"];
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[s1.subThingies addObject:@"2"];
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NSData *data1 = [NSKeyedArchiver archivedDataWithRootObject:s1];//将s1序列化后,保存到NSData中
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[data1 writeToFile:@"/tmp/data.txt" atomically:YES];//持久化保存成物理文件
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NSData *data2 = [NSData dataWithContentsOfFile:@"/tmp/data.txt"];//读取文件
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Sample *s2 = [NSKeyedUnarchiver unarchiveObjectWithData:data2];//反序列化
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