iOS开发-数据存储

                
                    //
                    偏好设置NSUserDefaults
    
                    //
                    底层就是封闭了一个字典,利用字典的方式生成plist文件
    
                    //
                    好处:不需要关心文件名(它会自动生成)快速进行键值对存储.
    NSUserDefaults *defautls = [NSUserDefaults standardUserDefaults];
    [defautls setObject:@"gaowei" forKey:@"name"];
    [defautls setBool:YES forKey:@"isBool"];
    [defautls setInteger:5 forKey:@"num"];
    //同步,立即写入文件.
    [defautls synchronize];
            

                
                    //
                    存是用什么key存的, 读的时候就要用什么key值取
    
                    //
                    存的时候使用的什么类型,取的时候也要用什么类型.
    NSString *str = [[NSUserDefaults standardUserDefaults] objectForKey:@"name"];
    BOOL isBool  = [[NSUserDefaults standardUserDefaults] boolForKey:@"isBool"];
    NSInteger num = [[NSUserDefaults standardUserDefaults] integerForKey:@"num"];
    NSLog(@"name =%@-isBool=%d-num=%ld",str,isBool,num);
            

                
                    //
                    获取沙盒的路径 person.data 随便写
   NSString *path = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)[0];
   NSString *filePathName =  [path stringByAppendingPathComponent:@"person.data"];

//    Person *per = [[Person alloc] init];
//    per.name = @"xmg";
//    per.age = 10;
    Student *stu = [[Student alloc] init];
    stu.name = @"gxq";
    stu.age = 10;
    stu.height = 150;

    Dog *dog = [[Dog alloc] init];
    dog.name = @"wangcai";

    stu.dog = dog;

    //归档
    //archiveRootObject执行这个方法时, 底层会调用要存的对象的encodeWithCoder方法,
    //调用encodeWithCoder目的就是想询问下要存对象的哪些属性.怎么存.
    [NSKeyedArchiver archiveRootObject:stu toFile:filePathName];
            

                
                    //
                    获取沙盒的路径
    NSString *path = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)[0];
    NSString *filePathName =  [path stringByAppendingPathComponent:@"person.data"];

    //解档
    //unarchiveObjectWithFile执行这个方法时,底层会调用要存的对象的initWithCoder方法,
    //调用initWithCoder目的就是想询问下要取对象的哪些属性.
    Student *per = [NSKeyedUnarchiver unarchiveObjectWithFile:filePathName];
            

                
                    //
                    注意点: 不管是自定义的类对象"per”,继承的类对象”stu”,包含的类对象”dog”,只要归档的时候,都要实现encodeWithCoder,解档就要实现initWithCoder

                    //
                    必须得要遵守NSCoding协议才行
-(void)encodeWithCoder:(NSCoder *)encoder{
    [encoder encodeObject:self.name forKey:@"name"];
    [encoder encodeInt:self.age forKey:@"age"];
}
//当解析一个文件时就会调用.
-(instancetype)initWithCoder:(NSCoder *)decoder{
    if (self = [super init]) {
       self.name = [decoder decodeObjectForKey:@"name"];
       self.age =  [decoder decodeIntForKey:@"age"];
    }
    return self;
}