简单的归档解档

我们想要长久保存自定义对象数据，那么就少不了对沙盒的操作。

屏幕快照 2017-11-14 下午10.14.03.png

屏幕快照 2017-11-14 下午10.20.12.png

获得路径的方式 Documents , Library , tmp

Documents ： iTunes 会备份，苹果也不允许保存东西在这里面。会被拒
tmp ： 临时保存,随时可能被删除
Library : ----> 下面2个子目录
Caches ：缓存文件
Preferences：偏好设置 保存账号等信息 --> 经过我测试 [NSUserDefaults standardUserDefaults] 就是保存在这里的

//获取Caches路径
     NSArray *path1 = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    //获取Library路径
     NSArray *path2 = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
    //获取Documents路径
     NSArray *path3 = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

关于归档具体实现1，自定义对象 2， 数组，字典的归档

例子1：字典数组的归档

/**
   字典的存取 沙盒路径
 */
-(void)dicArchivie
{
    NSString *chahe = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
    NSString *path = [chahe stringByAppendingString:@"accont.plist"];
    NSDictionary *dic = @{@"name":@"xiaoming",@"age":@"18"};
    //存
    [dic writeToFile:path atomically:YES];
    NSLog(@"paths = %@",path);
    //取
    NSDictionary *dicM = [NSDictionary dictionaryWithContentsOfFile:path];
    NSLog(@"dicM = %@",dicM);
}

/*
@interface NSDictionary<__covariant KeyType, __covariant ObjectType> : NSObject <NSCopying, NSMutableCopying, NSSecureCoding, NSFastEnumeration>
这是字典的归档，直接归档到沙盒 cache路径文件下面
从这里可以看出 ，要遵循 NSCoding,NSCopying 
*/

例子2：自定义对象的归档解档，我们归档一个person类。

//这是person.h
#import <Foundation/Foundation.h>
@interface Person : NSObject<NSCoding,NSCopying>
@property (nonatomic,copy)NSString *name ;
@property (nonatomic,copy)NSString *age;
@property (nonatomic,assign)CGFloat weight;
@end

//这是person.m 实现
#import "Person.h"
#import <objc/runtime.h>
@interface Person ()
@end
@implementation Person
 //方式 1 ，runtime 快速归档
#if 0
//这是runtime 的方法 NSCoding 实现归档的协议
-(void)encodeWithCoder:(NSCoder *)aCoder
{
    unsigned int count = 0;
    Ivar *ivars = class_copyIvarList([self class], &count); //获取所有的属性
    for (int i = 0; i<count; i++) {
        //取出变量
        Ivar ivar = ivars[i];
        //查看变量的名字
        NSString *name = [NSString stringWithUTF8String:ivar_getName(ivar)];
        //查看变量的类型
        //NSString *type = [NSString stringWithUTF8String:ivar_getTypeEncoding(ivar)];
        //  利用KVC取出属性对应的值
        id value = [self valueForKey:name];
        //实现归档
        [aCoder encodeObject:value forKey:name];
    }
    //  记住C语言中copy出来的要进行释放
    free(ivars);
}

//解档
-(instancetype)initWithCoder:(NSCoder *)aDecoder
{
    if (self =[super init]) {
        unsigned int count = 0;
        Ivar *ivars = class_copyIvarList([self class], &count);
        for (int i = 0; i<count; i++) {
            //取出变量
            Ivar ivar = ivars[i];
            //查看变量的名字
            NSString *name = [NSString stringWithUTF8String:ivar_getName(ivar)];
            //取出变量的值
            id value = [aDecoder decodeObjectForKey:name];
            //KVC 赋值
            [self setValue:value forKeyPath:name];
        }
        free(ivars);
    }
    return self;
}
#endif

//---------------------------------------------------------------------------
//方式2
-(void)encodeWithCoder:(NSCoder *)aCoder
{
        [aCoder encodeObject:self.name forKey:@"name"];
        [aCoder encodeObject:self.age forKey:@"age"];
        [aCoder encodeObject:@(self.weight) forKey:@"weight"];
}

//解档
-(instancetype)initWithCoder:(NSCoder *)aDecoder
{
    if (self =[super init]) {
        self.name = [aDecoder decodeObjectForKey:@"name"];
        self.age = [aDecoder decodeObjectForKey:@"age"];
        self.weight = [[aDecoder decodeObjectForKey:@"weight"] doubleValue];
    }
    return self;
}

//这是ViewController 调用方法
/**
    自定义对象的沙盒存取  NSKeyedArchiver 必须用这个
 */
-(void)customObject
{
    Person *p = [Person new];
    p.name = @"小明";
    p.age = @"14";
    p.weight = 55;
    
    NSString *chahe = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
    NSString *path = [chahe stringByAppendingString:@"accton.archive"];
    NSLog(@"path = %@",path) ;
    //自定义对象的存储必须用 NSKeyedArchiver  不能用 writeToFile
    //writeToFile适用 NSArray 和 NSDictionary
    [NSKeyedArchiver archiveRootObject:p toFile:path]; //自定义对象   沙盒 存
    Person *person =  [NSKeyedUnarchiver unarchiveObjectWithFile:path];// 自定义对象   沙盒 取
    NSLog(@"%@ %@ %f" ,person.name,person.age,person.weight);
        //这里copy Person 必须实现NSCoying
//    Person *p1 = [Person mutableCopy];
//    NSLog(@"p1.name = %@" ,p1.name);
}

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