1梦鉴、對(duì)象歸檔

所謂對(duì)象歸檔集绰，類(lèi)似于“序列化”機(jī)制，歸檔就是用某種格式把一個(gè)或多 個(gè)對(duì)象保存到指定文件中，方便以后從文件中恢復(fù)他們嚼贡。

1.1 使用NSKeyedArchiver歸檔

NSKeyedArchiver和NSKeyedUnarchiver

對(duì)系統(tǒng)類(lèi)型直接歸檔

archiveRootObject: toFile:
unarchiveObjectWithFile:

//對(duì)象歸檔
- (void)test5{
    //第一種方法队询，直接調(diào)用NSKeyedArchiver
    //先創(chuàng)建一個(gè)NSDictionary對(duì)象
    NSDictionary *dict = @{
                           @"Objective-C" : @89,
                           @"Rubby" : @69,
                           @"Python" : @75,
                           @"Perl" : @109
                           };
    // 對(duì)dict對(duì)象進(jìn)行歸檔
    NSString *filePath = @"/Users/lwg/Desktop/SettingBundle/SettingBundle/dict.archive";
    [NSKeyedArchiver archiveRootObject:dict toFile:filePath];
    
    // 讀取dict.archive
    NSDictionary *dict1 = [NSKeyedUnarchiver unarchiveObjectWithFile:filePath];
    NSLog(@"%@",dict1);
    
}

1.2 實(shí)現(xiàn)NSCoding協(xié)議

一般來(lái)說(shuō)，如果對(duì)象的實(shí)例變量是OC基本類(lèi)型，并且實(shí)現(xiàn)了NSCoding協(xié)議，則可直接調(diào)用encodingObject:forKey:方法來(lái)歸檔該實(shí)例變量，使用decodeObjectForKey:方法恢復(fù)該實(shí)例變量即可擎厢。
如果需要?dú)w檔、恢復(fù)任意自定義類(lèi)的實(shí)例辣吃，那么該類(lèi)型應(yīng)該實(shí)現(xiàn)NSCoding協(xié)議如下兩個(gè)方法：

initWithCoder:
encodeWithCoder:

@interface FKApple : 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

方法實(shí)現(xiàn)
- (void)encodeWithCoder:(NSCoder *)aCoder{
    //調(diào)用NSCoder的方法歸檔該對(duì)象的每個(gè)實(shí)例變量
    [aCoder encodeObject:_color forKey:@"color"];
    [aCoder encodeDouble:_weight forKey:@"weight"];
    [aCoder encodeInt:_size forKey:@"size"];
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder{
    // 使用NSCoder恢復(fù)color动遭、weight、size這3個(gè)key
    // 所對(duì)應(yīng)的value神得，并將恢復(fù)的value賦給當(dāng)前對(duì)象的3個(gè)實(shí)例變量
    _color = [aDecoder decodeObjectForKey:@"color"];
    _weight = [aDecoder decodeDoubleForKey:@"weight"];
    _size = [aDecoder decodeIntForKey:@"size"];
    return self;
}

1.3使用NSData完成自定義歸檔

上面的方法每次只能將單個(gè)對(duì)象作為root進(jìn)行歸檔或者恢復(fù)厘惦，如果希望一次性收集多個(gè)對(duì)象，并進(jìn)行歸檔到單個(gè)文件中哩簿，可以使用NSMutableData來(lái)創(chuàng)建NSKeyedArchiver和NSKeyedUnarchiver對(duì)象宵蕉。
步驟如下：
1.以NSMutableData作為參數(shù)，創(chuàng)建NSKeyedArchiver對(duì)象节榜；
2.重復(fù)調(diào)用NSKeyedArchiver對(duì)象的encodeObject：forKey：方法來(lái)歸檔所有需要?dú)w檔到一個(gè)文件中的對(duì)象羡玛。
3.調(diào)用NSKeyedArchiver對(duì)象的finishEncoding方法結(jié)束歸檔；
4.根據(jù)需要宗苍，程序可以選擇將保存歸檔數(shù)據(jù)的NSData通過(guò)網(wǎng)絡(luò)傳輸或者輸出到磁盤(pán)文件上稼稿。

// 使用NSData完成自定義歸檔
// 一次性將多個(gè)對(duì)象歸檔到單個(gè)文件中
- (void)test6{
    //先創(chuàng)建一個(gè)NSDictionary對(duì)象
    NSDictionary *dict = @{
                           @"Objective-C" : @89,
                           @"Rubby" : @69,
                           @"Python" : @75,
                           @"Perl" : @109
                           };
    // 創(chuàng)建一個(gè)NSSet對(duì)象
    NSSet *set = [NSSet setWithObjects:@"ios",@"Java",@"OC", nil];
    FKApple *apple = [[FKApple alloc] initWithColor:@"紅色" weight:3.4 size:20];
    // 創(chuàng)建一個(gè)NSMutableData對(duì)象，用于保存歸檔數(shù)據(jù)
    NSMutableData *data = [NSMutableData data];
    NSKeyedArchiver *arch = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
    
    // 重復(fù)調(diào)用此方法
    [arch encodeObject:dict forKey:@"dict"];
    [arch encodeObject:set forKey:@"set"];
    [arch encodeObject:apple forKey:@"apple"];
    
    [arch finishEncoding];
    
    // 程序?qū)SData緩存區(qū)保存的數(shù)據(jù)寫(xiě)入文件
     NSString *filePath = @"/Users/lwg/Desktop/SettingBundle/SettingBundle/multi.archive";
    if ([data writeToFile:filePath atomically:YES] == NO) {
        NSLog(@"歸檔失敾淇摺让歼！");
    }
    
    // 讀取歸檔
    NSData *data1 = [NSData dataWithContentsOfFile:filePath];
    NSKeyedUnarchiver *unarch = [[NSKeyedUnarchiver alloc] initForReadingWithData:data1];
    NSDictionary *dict1 = [unarch decodeObjectForKey:@"dict"];
    NSSet *set1 = [unarch decodeObjectForKey:@"set"];
    FKApple *apple1 = [unarch decodeObjectForKey:@"apple"];
    [unarch finishDecoding];
    NSLog(@"%@",dict1);
    NSLog(@"%@",set1);
    NSLog(@"%@",apple1);
}

1.4使用歸檔實(shí)現(xiàn)深復(fù)制

當(dāng)程序歸檔一個(gè)對(duì)象時(shí)，系統(tǒng)會(huì)把該對(duì)象關(guān)聯(lián)的所有數(shù)據(jù)都轉(zhuǎn)化為字節(jié)數(shù)據(jù)挪钓；如果程序從這些字節(jié)數(shù)據(jù)中恢復(fù)該對(duì)象是越，恢復(fù)出來(lái)的對(duì)象與原對(duì)象完全相同耳舅，但沒(méi)有任何公用的部分碌上，這就實(shí)現(xiàn)了深復(fù)制倚评。

// 利用歸檔實(shí)現(xiàn)深復(fù)制
- (void)deepCopy{
    NSDictionary *dict = @{
                           @"one" : [[FKApple alloc] initWithColor:@"紅色" weight:3.4 size:20],
                           @"two" : [[FKApple alloc] initWithColor:@"綠色" weight:2.8 size:14]
                           };
    // 將歸檔對(duì)象的數(shù)據(jù)寫(xiě)入NSData
    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:dict];
    // 從NSData對(duì)象中恢復(fù)對(duì)象，這樣既可完成深復(fù)制
    NSDictionary *dictCopy = [NSKeyedUnarchiver unarchiveObjectWithData:data];
    // 獲取復(fù)制后的對(duì)象
    FKApple *app = [dictCopy objectForKey:@"one"];
    // 修改對(duì)象屬性
    [app setColor:@"紫色"];
    
    // 獲取原始對(duì)象
    FKApple *oneApp = [dict objectForKey:@"one"];
    // 訪(fǎng)問(wèn)該對(duì)象顏色馏予，發(fā)現(xiàn)并沒(méi)有改變
    NSLog(@"dict中key為one對(duì)應(yīng)的顏色為:%@,復(fù)制后的app顏色為:%@",oneApp.color,app.color);
    
}