iOS的归档与解档

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归档与解档也是iOS中对象保存与读取的一种方式，对系统的对象归档与解档比较容易，而对自定义类的对象就要继承协议。

1.系统对象的解档与归档

        NSString *path = @"/Users/gph/Desktop/1.plist";        NSArray *array = [[NSArray alloc]initWithObjects:@"One",@"Two",@"Three", nil];        NSDictionary *dic = [[NSDictionary alloc]initWithObjectsAndKeys:@"One",@"1",@"Two",@"2",@"Three",@"3", nil];        //归档        NSMutableData *data = [[NSMutableData alloc]init];        NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data];        [archiver encodeObject:array forKey:@"array"];        [archiver encodeObject:dic forKey:@"dic"];                [archiver finishEncoding];        [data writeToFile:path atomically:YES];                //解档        NSData *data2 = [[NSData alloc]initWithContentsOfFile:path];        NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc]initForReadingWithData:data2];                NSDictionary *tmpDic = [unarchiver decodeObjectForKey:@"dic"];        NSArray *tmpArr = [unarchiver decodeObjectForKey:@"array"];                NSLog(@"%@",tmpArr);        NSLog(@"%@",tmpDic);

2.自定义类的对象解档与归档

一个完整的应用需要考虑方方面面，比如内存警告，比如转入后台,就要将对象进行保存。但对自定义类对象归档的步骤与前面类似，差别是先继承NSCoding协议,先定义一个UserItem类。UserItem.h文件如下

#import <Foundation/Foundation.h>@interface UserItem : NSObject<NSCoding>@property (nonatomic, copy) NSString* name;@end

UserItem.m文件如下

@implementation UserItem//归档- (id)initWithCoder:(NSCoder *)aDecoder{    self.name = [aDecoder decodeObjectForKey:@"name"];    return self;}//解档- (void)encodeWithCoder:(NSCoder *)aCoder{    [aCoder encodeObject:self.name forKey:@"name"];}@end

归档与解档代码：

    UserItem* user = [[UserItem alloc] init];    user.name = @"独孤求败";    NSMutableData* data = [[NSMutableData alloc]init];    NSKeyedArchiver* archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];    [archiver encodeObject:user forKey:@"user"];    [archiver finishEncoding];        //从data里面拿出对象    NSKeyedUnarchiver* unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];    UserItem* user2 = [unarchiver decodeObjectForKey:@"user"];    [unarchiver finishDecoding];    NSLog(@"%@",user2.name);

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