OC-簡單介紹KVC和簡單的使用!

    //基本的KVC(Key,Value,Coding)基本概念
    Person *person = [[Person alloc] init];
    
    
    //下面會先判斷getter/setter方法是否存在 如果存在先會調用getter/setter方法
    [person setValue:@"1" forKey:@"compatibility"];
    
    //valueForKey獲取對象的數值 如果存儲的是基本數據類型 必須先轉換成對象 然後對象轉換基本數據類型
    NSNumber *number =  [person valueForKey:@"compatibility"];
    
    //設置對象
    [person setValue:[Car new] forKey:@"car"];
    
    //設置當前Person裏面的cat對象的屬性
    [person setValue:[NSNumber numberWithInt:1] forKeyPath:@"car.status"];
    //獲取
    NSNumber *num1 = [person valueForKeyPath:@"car.status"];
    
    //創建第一本書
    book *book1 = [[book alloc] init];
    [book1 setValue:@"三國演義" forKey:@"name"];
    [book1 setValue:[NSNumber numberWithInt:124] forKey:@"price"];
    
    //創建第二本書
    book *book2 = [[book alloc] init];
    [book2 setValue:@"三國演義" forKey:@"name"];
    [book2 setValue:[NSNumber numberWithInt:125] forKey:@"price"];
    
    //創建包含書籍對象
    NSArray *array = [[NSArray alloc] initWithObjects:book1,book2,nil];
    //設置屬性
    [person setValue:array forKey:@"array"];
    
    //KVC可以做一些簡單的運算 存儲的數量
    NSLog(@"%@",[person valueForKeyPath:@"array.@count"]);
    //總和
    NSLog(@"%@",[person valueForKeyPath:@"[email protected]"]);
    //平均
    NSLog(@"%@",[person valueForKeyPath:@"[email protected]"]);
    //最大
    NSLog(@"%@",[person valueForKeyPath:@"[email protected]"]);
    //最小
    NSLog(@"%@",[person valueForKeyPath:@"[email protected]"]);