-(void)encodeWithCoder:(NSCoder *)encoder{
    
    unsigned int count = 0;
    //取出Person这个对象的所有属性
    Ivar *ivars = class_copyIvarList([self class], &count);
    //对所有属性进行遍历
    for (int i = 0; i<count; i++) {
        // 取出i位置对应的成员变量
        Ivar ivar = ivars[i];
        // 查看成员变量
        const char *name = ivar_getName(ivar);
        // 归档
        NSString *key = [NSString stringWithUTF8String:name];
        id value = [self valueForKey:key];
        [encoder encodeObject:value forKey:key];
        
    }
    free(ivars);
}

-(id)initWithCoder:(NSCoder *)decoder{
    
    if (self = [super init]) {
        unsigned int count = 0;
        Ivar *ivars = class_copyIvarList([self class], &count);
        for (int i = 0; i<count; i++) {
            // 取出i位置对应的成员变量
            Ivar ivar = ivars[i];
            // 查看成员变量
            const char *name = ivar_getName(ivar);
            // 归档
            NSString *key = [NSString stringWithUTF8String:name];
            id value = [decoder decodeObjectForKey:key]; 
            // 设置到成员变量身上
            [self setValue:value forKey:key];
        }
        free(ivars);
    }
    return self;
}