30 Foundation框架之NSKeyedArchiver和NSKeyedUnarchiver

Tags: Objective-C

---

NSKeyedArchiver表示归档，表示把对象转换为可保存可传输的数据流，通常可以是文件或者URL。
NSKeyedUnarchiver表示恢复归档，表示从数据流中恢复对象。

NSKeyedArchiver和NSKeyedUnarchiver有两种使用方式，第一种是使用类方法创建将对象当成root进行归档和恢复，代码示例如下：
test1.m

#import <Foundation/Foundation.h>int main(int argc, const char * argv[]) {    @autoreleasepool {        NSDictionary *dict1 = [NSDictionary dictionaryWithObjectsAndKeys:                              [NSNumber numberWithInt:89], @"C++",                              [NSNumber numberWithInt:79], @"C",                              [NSNumber numberWithInt:69], @"Java",                              [NSNumber numberWithInt:59], @"Swift",nil];        //使用NSKeyedArchiver的类方法进行归档        [NSKeyedArchiver archiveRootObject:dict1 toFile:@"/Users/Ralf/Desktop/myDict.archive"];//归档至文件中        NSData *dataArchive = [NSKeyedArchiver archivedDataWithRootObject:dict1];//归档至Data中        //使用NSKeyedUnarchiver的类方法恢复归档中的对象        NSDictionary *dict20 = [NSKeyedUnarchiver unarchiveObjectWithFile:@"/Users/Ralf/Desktop/myDict.archive"];//从文件中恢复对象        NSDictionary *dict21 = [NSKeyedUnarchiver unarchiveObjectWithData:dataArchive];//从NSData中恢复对象        NSLog(@"C++对应的value为：%@", [dict20 valueForKey:@"C++"]);        NSLog(@"C对应的value为：%@", [dict20 valueForKey:@"C"]);        NSLog(@"Java对应的value为：%@", [dict20 valueForKey:@"Java"]);        NSLog(@"Swift对应的value为：%@", [dict20 valueForKey:@"Swift"]);        NSLog(@"C++对应的value为：%@", [dict21 valueForKey:@"C++"]);        NSLog(@"C对应的value为：%@", [dict21 valueForKey:@"C"]);        NSLog(@"Java对应的value为：%@", [dict21 valueForKey:@"Java"]);        NSLog(@"Swift对应的value为：%@", [dict21 valueForKey:@"Swift"]);    }    return 0;}

运行结果：

C++对应的value为：89C对应的value为：79Java对应的value为：69Swift对应的value为：59C++对应的value为：89C对应的value为：79Java对应的value为：69Swift对应的value为：59

---

当需要归档、恢复某个自定义类的对象的实例时，那么该类必须实现<NSCoding>协议，也即在类的实现部分必须实现该协议的如下两个方法：
1. initWithCoder:：该方法负责恢复对象，在该方法中要恢复该对象的所有实例变量
2. encodeWithCoder:：该方法负责归档该对象，在该方法中要归档该对象的所有实例变量

如果针对一些基础数据类型时，该怎么归档和恢复呢？OC提供了如下方法：

代码示例如下：
GKHApple.h

#import <Foundation/Foundation.h>@interface GKHApple : NSObject <NSCoding>@property (nonatomic, copy) NSString *color;@property (nonatomic, assign) double weight;@property (nonatomic, assign) int size;- (id) initWithColor:(NSString *)color weight:(double)weight size:(int)size;@end

GKHApple.m

#import "GKHApple.h"@implementation GKHApple- (id) initWithColor:(NSString *)color weight:(double)weight size:(int)size {    if (self = [super init]) {        self.color = [color copy];        self.weight = weight;        self.size = size;    }    return self;}- (NSString *) description {    return [NSString stringWithFormat:@"<GKHApple[_color=%@, _weight=%g, _size=%d]>", self.color, self.weight, self.size];}//实现该类的对象的归档方法- (void) encodeWithCoder:(NSCoder *)aCoder {    //调用NSCoder的方法归档对象的每个实例变量    [aCoder encodeObject:_color forKey:@"color"];    [aCoder encodeDouble:_weight forKey:@"weight"];    [aCoder encodeInt:_size forKey:@"size"];}//实现该类的对象的恢复归档的方法- (id) initWithCoder:(NSCoder *)aDecoder {    //调用NSCoder的方法恢复归档到对象的每个实例变量    [aDecoder decodeObjectForKey:@"color"];    [aDecoder decodeDoubleForKey:@"weight"];    [aDecoder decodeIntForKey:@"size"];    return self;}@end

test2.m

#import <Foundation/Foundation.h>#import "GKHApple.h"int main(int argc, const char * argv[]) {    @autoreleasepool {        NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:                               [NSNumber numberWithInt:89], @"C++",                               [NSNumber numberWithInt:79], @"C",                               [NSNumber numberWithInt:69], @"Java",                               [NSNumber numberWithInt:59], @"Swift",nil];        NSSet *set = [NSSet setWithObjects:@"C++编程", @"C编程", @"Java编程", @"Swift编程", nil];        GKHApple *apple = [[GKHApple alloc] initWithColor:@"red" weight:3.4 size:20];        //创建一个NSMutableData用来保存归档的数据        NSMutableData *data = [NSMutableData data];        //①使用NSKeyedArchiver的实例方法创建归档        NSKeyedArchiver *arch = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data];        //②重复调用encodeObject:forKey:方法归档所有需要归档的对象        [arch encodeObject:dict forKey:@"myDict"];        [arch encodeObject:set forKey:@"mySet"];        [arch encodeObject:apple forKey:@"myApple"];        //③结束归档        [arch finishEncoding];        //将归档的NSMutableData的数据写入文件        if ([data writeToFile:@"multi.archive" atomically:YES] == NO) {            NSLog(@"归档失败");        }        //创建一个NSData用来读取指定文件的归档数据        NSData *data1 = [NSData dataWithContentsOfFile:@"multi.archive"];        //①使用NSKeyedUnarchiver的实例方法创建解归档对象        NSKeyedUnarchiver *unarch = [[NSKeyedUnarchiver alloc]initForReadingWithData:data1];        //②重复调用decodeObjectForKey:方法恢复归档中的对象        [unarch decodeObjectForKey:@"myDict"];        [unarch decodeObjectForKey:@"mySet"];        [unarch decodeObjectForKey:@"myApple"];        //③结束解归档        [unarch finishDecoding];        NSLog(@"%@", dict);        NSLog(@"%@", set);        NSLog(@"%@", apple);    }    return 0;}

运行结果为：

{    C = 79;    "C++" = 89;    Java = 69;    Swift = 59;}{(    "Java\U7f16\U7a0b",    "Swift\U7f16\U7a0b",    "C++\U7f16\U7a0b",    "C\U7f16\U7a0b")}<GKHApple[_color=red, _weight=3.4, _size=20]>