归档反归档 - 本地沙盒存储复杂对象

　　NSString，NSNumber，NSArray，NSDictionary等简单对象可以方便的存储在本地沙盒文件中，而复杂的对象，诸如属性、方法较多的类对象，就需要使用归档反归档方法（序列化与反序列化），以NSData方式进行存储。

　　归档反归档，主要的操作顺序是：编码(enCoding) -> 归档(archiver) -> 解码(deCoding) -> 反归档(unarchiver)

　　1.编码与解码的方法，需要在类的声明文件中接受<NSCoding>协议，在实现文件.m中完成协议方法:　　

/*
 * Model.h 接受NSCoding协议 
 */

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface Model : NSObject<NSCoding>
@property(nonatomic,strong)NSString *name;
@property(nonatomic,assign)NSInteger num;

- (instancetype)initWithName:(NSString *)name num:(NSInteger)num;
@end

/*
 * Model.m 实现编码与解码的协议方法 
 */

#import "Model.h"

@implementation Model
- (instancetype)initWithName:(NSString *)name num:(NSInteger)num{
    self = [super init];
    if(self){
        self.name = name;
        self.num = num;
    }
    return self;
}

// 编码
- (void)encodeWithCoder:(NSCoder *)aCoder{
    [aCoder encodeObject:self.name forKey:@"name"];
    [aCoder encodeObject:@(self.num) forKey:@"num"];
}

// 解码
- (instancetype)initWithCoder:(NSCoder *)aDecoder{
    self = [super init];
    if(self){
        self.name = [aDecoder decodeObjectForKey:@"name"];
        self.num = [[aDecoder decodeObjectForKey:@"num"] integerValue];
    }
    return self;
}

@end

　　2.归档 - 保存复杂对象；反归档 - 获取对象

#import "ViewController.h"
#import "Model.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *image;
@property (weak, nonatomic) IBOutlet UITextField *nameText;
@property (nonatomic,strong)NSString *path;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // 获取沙盒路径
    self.path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0] stringByAppendingPathComponent:@"data.data"];
}

// 归档保存对象
- (IBAction)save:(UIButton *)sender {
    // 创建对象
    Model *m = [[Model alloc] initWithName:@"测试" num:101];
    
    // 创建NSData(可变),NSKeyedArchiver(实现归档的对象)
    NSMutableData *data = [NSMutableData data];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
    
    // 对象进行编码归档
    [archiver encodeObject:m forKey:@"m"];
    
    // 归档完成(必需)
    [archiver finishEncoding];
    
    // 写入沙盒路径文件中
    [data writeToFile:self.path atomically:YES];
}

// 反归档解码获取对象
- (IBAction)get:(UIButton *)sender {
    // 创建NSData(可变), NSKeyedUnarchiver(实现反归档的对象)
    NSMutableData *data = [NSMutableData dataWithContentsOfFile:self.path];
    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
    
    // 反归档解码获取对象
    Model *m = [unarchiver decodeObjectForKey:@"m"];
    
    self.nameText.text = [NSString stringWithFormat:@"%@ %ld", m.name, m.num];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

　　*.主要沙盒路径:

NSHomeDirectory----------------------->沙盒主路径
NSDocumentDirectory------------------->Documents文件夹
NSLibraryDirectory-------------------->Library文件夹
NSCachesDirectory--------------------->Caches文件夹
NSTemporaryDirectory------------------>tmp文件夹