ios UIView父子关系和层次结构

今天我们来认识下UIView的父子关系。老样子首先在BOOL返回值下面创建窗口。

然后我们先来创建一个视图

-(void)createviews

{

    //父视图

    UIView *redview =[ [UIView alloc]init];

    redview.frame = CGRectMake(20,40,300,400);

    redview.backgroundColor = [UIColor redColor];

    [self.window addSubview:redview];

   //子视图

    UIView *blueview = [[UIView alloc]init];

    blueview.frame = CGRectMake(20,20,250,100);

    blueview.backgroundColor = [UIClor blueColor];

    [redview addSubview:blueview];

   UIView *greenview = [[UIView alloc]init];

   greenview.frame = CGRectMake (40,20,50,300);

   greenview.backgroundColor = [UIColor greenColor];

   [redview addSubview:greenview];

  [redview addSubview:b