歸檔

一：什麼是歸檔

對象歸檔是將對象歸檔以文件的形式保存到磁盤中(也稱爲序列化，持久化)使用的時候讀取該文件的保存路徑讀取文件的內容（也稱爲接檔，反序列化）

對象歸檔的文件是保密的磁盤上沒法查看文件中的內容，而屬性列表是明文的能夠查看

1，使用archiveRootObject進行簡單地歸檔和解檔（對一個對象進行歸檔）

- (void)viewDidLoad {

    [super viewDidLoad];

    NSString *str = @"afa";

    NSString *astr = @"111";

    NSArray *Array = [NSArray arrayWithObjects:str, astr, nil];

    //歸檔

    NSString *Path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

    NSString *filename = [Path stringByAppendingPathComponent:@"test"];

    [NSKeyedArchiver archiveRootObject:Array toFile:filename];

    

    //解檔

    NSArray *arr = [NSKeyedUnarchiver unarchiveObjectWithFile: filename];

    str = [arr objectAtIndex:0];

    astr =  [arr objectAtIndex:1];

    NSLog(@"str:%@",str);

    NSLog(@"astr:%@",astr);

 }

2，對多個對象的歸檔（對基本類型數據）

歸檔（寫入數據）

 step1:準備數據

CGPoint point = CGPointMake(1.0, 2.0);
NSString *info = @"座標原點";
NSInteger value = 10;
NSString *multiHomePath = [NSHomeDirectory() stringByAppendingPathComponent:@"multi.archiver"];
NSMutableData *data = [[NSMutableData alloc]init];
NSKeyedArchiver *archvier = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data];

step2:對多個對象進行歸檔  

[archvier encodeCGPoint:point forKey:@"kPoint"];
[archvier encodeObject:info forKey:@"kInfo"];
[archvier encodeInteger:value forKey:@"kValue"];
[archvier finishEncoding];
[data writeToFile:multiHomePath atomically:YES];

解檔（路徑中得到數據構造NSKeyedUnarchiver實例，使用decodeXXXForKey方法得到文件中的對象。）

NSMutableData *dataR = [[NSMutableData alloc]initWithContentsOfFile:multiHomePath];
NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc]initForReadingWithData:dateR];
CGPoint pointR = [unarchiver decodeCGPointForKey:@"kPoint"];
NSString *infoR = [unarchiver decodeObjectForKey:@"kInfo"];
NSInteger valueR = [unarchiver decodeIntegerForKey:@"kValue"];
[unarchiver finishDecoding];
NSLog(@"%f,%f,%@,%d",pointR.x,pointR.y,infoR,valueR);

3，對自定義對象進行歸檔

step1：自定義一個實體類Archive

Archive.h

#import <Foundation/Foundation.h>

@interface Archive : NSObject
@property (copy,nonatomic) NSString *name;
@property NSInteger age;
@property (copy,nonatomic) NSString *address;
@property (copy,nonatomic) UIImage *photo;

@end

 

Archive實現了三個委託方法1）encodeWithCoder: 2）initWithCoder:  3）copyWithZone:

1)encodeWithCoder

Encodes the receiverusing a given archiver

經過一個給定的archiver把消息接收者進行編碼。

當接收到encodeObject消息的時候，類終端encodeWithCoder方法被調用。

2)initWithCoder

Returns an objectinitialized from data in a given unarchiver. (required)

從一個給定unarchiver的數據中返回一個初始化對象。

3）copyWithZone

Returnsa new instance that’s a copy of the receiver

返回消息接收者的一個複製的新實例。

SDK的概念就是這樣，下面看看這個自定義類歸檔的具體代碼，其實和多個對象的歸檔是同樣的。。。

 

step2：歸檔：

//保存圖片與歸檔
- (IBAction)save:(id)sender {

    //準備數據
    NSString *name = @"小楊在玩iOS";
    NSInteger age = 22;
    NSString *address = @"你猜我在哪~";
    UIImage *photo = [UIImage imageNamed:@"loginman.jpg"];
    //存儲數據到類
    Archive *archivingData = [[Archive alloc] init];
    archivingData.name = name;
    archivingData.age = age;
    archivingData.address = address;
    archivingData.photo = photo;

    //歸檔
    NSMutableData *data = [[NSMutableData alloc] init];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];

    [archiver encodeObject:archivingData forKey:kArchivingDataKey]; // archivingDate的encodeWithCoder
方法被調用
    [archiver finishEncoding];
    //寫入文件
    [data writeToFile:self.archivingFilePath atomically:YES];
}

 

step3：接檔：

- (IBAction)loadArchive:(id)sender {
    NSData *data = [[NSMutableData alloc] initWithContentsOfFile:self.archivingFilePath];
    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];

    //得到類
    Archive *archivingData = [unarchiver decodeObjectForKey:kArchivingDataKey];// initWithCoder方法被調用
    [unarchiver finishDecoding];

    //讀取的數據
    NSString *name = archivingData.name;
    NSInteger age = archivingData.age;
    NSString *address = archivingData.address;
    self.imageView.image = archivingData.photo;
    NSLog(@"%@||%d||%@",name,age,address);
}