//1.创建window

    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

    // Override point for customization after application launch.

    

    //2.设置window的属性(例如:背景颜色)

    self.window.backgroundColor = [UIColor whiteColor];

    

    //3.设置window为主窗口,并显示

    [self.window makeKeyAndVisible];

    /*

        //步骤1.开辟内存,并初始化(坐标和尺寸)

    UIView *yelloView = [[UIView alloc] initWithFrame:CGRectMake(50, 50, 100, 100)];

        //步骤2.设置视图的属性

    [yelloView setBackgroundColor:[UIColor yellowColor]];

        //步骤3.添加到window上

    [self.window addSubview:yelloView];

        //步骤4.释放内存

    [yelloView release];

        //(50, 200, 100, 100) 蓝色

    

    UIView *blueView = [[UIView alloc] initWithFrame:CGRectMake(50, 200, 100, 100)];

        //背景颜色默认是透明的 (cleanColor)

    blueView.backgroundColor = [UIColor blueColor];

    [self.window addSubview:blueView];//添加子视图

    [blueView release];

    

        //移除子视图

//    [blueView removeFromSuperview];

 

     //frame:是父视图的坐标系

        //改变父视图的位置,子视图也跟着移动

    UIView *greenView = [[UIView alloc] initWithFrame:CGRectMake(20, 30, 50, 50)];

    greenView.backgroundColor = [UIColor greenColor];

    [blueView addSubview:greenView];

    [greenView release];

    

    blueView.frame = CGRectMake(100, 250, 100, 100);

    

        //center :基于父视图的坐标系

    NSLog(@"%@", NSStringFromCGPoint(yelloView.center));

        //center.x = frame.origin.x + frame.size.width / 2;

        //center.y = frame.origin.y + frame.size.height / 2;

    

    //  bounds:基于自身的坐标系

    NSLog(@"%@", NSStringFromCGRect(yelloView.bounds));

        //frame,center,bounds

        //frame,bounds:CGRect

        //center:CGPoint

    

        //改变frame,影响center和bounds

        //改变center,bounds不变,影响frame

        //改变bounds,center不变,影响frame

    NSLog(@"改变前");

    NSLog(@"%@",NSStringFromCGRect(yelloView.frame));

    NSLog(@"%@", NSStringFromCGPoint(yelloView.center));

    NSLog(@"%@", NSStringFromCGRect(yelloView.bounds));

    

    yelloView.frame = CGRectMake(100, 100, 100, 100);

    NSLog(@"改变后");

    NSLog(@"%@",NSStringFromCGRect(yelloView.frame));

    NSLog(@"%@", NSStringFromCGPoint(yelloView.center));

    NSLog(@"%@", NSStringFromCGRect(yelloView.bounds));

    

    

    

//    hidden 显隐性,默认为NO

//YES 代表隐藏, 隐藏会影响子视图

    cView.hidden = YES;

        //不透明度 alpha.默认值是1.0

        //值越小,越透明,影响子视图

    aView.alpha = 0.5;

    aView.backgroundColor = [UIColor colorWithRed:1 green:1 blue:0 alpha:0.5];//仅改变该视图的alpha的透明度

//    aView.subviews

//    aView.superview

        //tag为视图添加整型标签,父视图可以通过标签,找到子视图

        //一般tag要大于100,避免和系统相同,并且tag要做到不重复(同一个父视图内)

    UIView *findView = [_window viewWithTag:1000];

        //__function__打印的的是函数的名字 __line__函数所在的行数