使用NSData读写多个对象

#import <Foundation/Foundation.h>
#import "MyClass.h"
#import "MyClass1.h"
//  对象的编码和解码（序列化和反序列化）
int main(int argc, const char * argv[]) {
    @autoreleasepool {
#warning 使用NSData读写多个对象
        NSMutableData *data;
        
        data = [NSMutableData data];//初始化NSMutableData
        NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data];//初始化NSKeyedArchiver
        MyClass1 *my2 = [[MyClass1 alloc]init];
        my2.value = 123;
        [archiver encodeObject:my forKey:@"myClass"];
        
        [archiver encodeObject:my2 forKey:@"myClass1"];
        
        [archiver finishEncoding];
        
        if([data writeToFile:@"two_objects" atomically:YES] == YES)
        {
            NSLog(@"两个对象存储成功.");
        }
        
        //  恢复MyClass和MyClass1
        NSData *data1;
        data1 = [NSData dataWithContentsOfFile:@"two_objects"];
        if(!data1)
        {
            NSLog(@"不能读取两个对象.");
            return 1;
        }
        NSKeyedUnarchiver *twoObjects;
        twoObjects = [[NSKeyedUnarchiver alloc]initForReadingWithData:data1];
        MyClass *myClass = [twoObjects decodeObjectForKey:@"myClass"];
        MyClass1 *myClass1 = [twoObjects decodeObjectForKey:@"myClass1"];
        [twoObjects finishDecoding];
        
        NSLog(@"myClass.email = %@", myClass.email);//myClass.email = bill@microsoft.com
        NSLog(@"myClass1.value = %d", myClass1.value);//myClass1.value = 123
            
    }
    return 0;
}

#import <Foundation/Foundation.h>

@interface MyClass1 : NSObject<NSCoding>
@property int value;
@end

#import "MyClass1.h"

@implementation MyClass1
@synthesize value;
//  编码
-(void)encodeWithCoder:(NSCoder *)aCoder
{
    [aCoder encodeObject:[NSNumber numberWithInt:value] forKey:@"key_value"];
}
//  解码
-(id)initWithCoder:(NSCoder *)aDecoder
{
    value = [[aDecoder decodeObjectForKey:@"key_value"] intValue];

    return self;
}
@end

#import <Foundation/Foundation.h>

@interface MyClass : NSObject<NSCopying,NSCoding>
@property (copy, nonatomic) NSString *name, *email;
@end

#import "MyClass.h"

@implementation MyClass
@synthesize name, email;
-(id)copyWithZone:(NSZone *)zone
{
    MyClass* my = [[MyClass allocWithZone:zone]init];
    my.name = name;
    my.email = email;
    return my;
}
//  编码
-(void)encodeWithCoder:(NSCoder *)aCoder
{
    [aCoder encodeObject:name forKey:@"key_name"];
    [aCoder encodeObject:email forKey:@"key_email"];
}
//  解码
-(id)initWithCoder:(NSCoder *)aDecoder
{
    name = [aDecoder decodeObjectForKey:@"key_name"];
    email = [aDecoder decodeObjectForKey:@"key_email"];
    return self;
}
@end