归档

一：什么是归档

对象归档是将对象归档以文件的形式保存到磁盘中(也称为序列化，持久化)使用的时候读取该文件的保存路径读取文件的内容（也称为接档，反序列化）

对象归档的文件是保密的磁盘上没法查看文件中的内容，而属性列表是明文的能够查看

1，使用archiveRootObject进行简单地归档和解档（对一个对象进行归档）

- (void)viewDidLoad {

    [super viewDidLoad];

    NSString *str = @"afa";

    NSString *astr = @"111";

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

    //归档

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

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

    [NSKeyedArchiver archiveRootObject:Array toFile:filename];

    

    //解档

    NSArray *arr = [NSKeyedUnarchiver unarchiveObjectWithFile: filename];

    str = [arr objectAtIndex:0];

    astr =  [arr objectAtIndex:1];

    NSLog(@"str:%@",str);

    NSLog(@"astr:%@",astr);

 }

2，对多个对象的归档（对基本类型数据）

归档（写入数据）

 step1:准备数据

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

step2:对多个对象进行归档  

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

解档（路径中得到数据构造NSKeyedUnarchiver实例，使用decodeXXXForKey方法得到文件中的对象。）

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，对自定义对象进行归档

step1：自定义一个实体类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实现了三个委托方法1）encodeWithCoder: 2）initWithCoder:  3）copyWithZone:

1)encodeWithCoder

Encodes the receiverusing a given archiver

经过一个给定的archiver把消息接收者进行编码。

当接收到encodeObject消息的时候，类终端encodeWithCoder方法被调用。

2)initWithCoder

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

从一个给定unarchiver的数据中返回一个初始化对象。

3）copyWithZone

Returnsa new instance that’s a copy of the receiver

返回消息接收者的一个复制的新实例。

SDK的概念就是这样，下面看看这个自定义类归档的具体代码，其实和多个对象的归档是同样的。。。

 

step2：归档：

//保存图片与归档
- (IBAction)save:(id)sender {

    //准备数据
    NSString *name = @"小杨在玩iOS";
    NSInteger age = 22;
    NSString *address = @"你猜我在哪~";
    UIImage *photo = [UIImage imageNamed:@"loginman.jpg"];
    //存储数据到类
    Archive *archivingData = [[Archive alloc] init];
    archivingData.name = name;
    archivingData.age = age;
    archivingData.address = address;
    archivingData.photo = photo;

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

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

 

step3：接档：

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

    //得到类
    Archive *archivingData = [unarchiver decodeObjectForKey:kArchivingDataKey];// initWithCoder方法被调用
    [unarchiver finishDecoding];

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