UIView详解1
一个UIView的实例就是一个视图，表示的是屏幕上的一块矩形区域，负责这块矩形区域的描绘以及和用户的交互。
第一、UIView的可视化属性
1. backgroundColor 背景属性
2. hidden 表示该view是否隐藏，
hidden属性为YES时视图隐藏，否则不隐藏。
在类的层次结构中，如果clipsTobounds设为YES,超出superView的部分subview就不会显示，否则会做显示， 默认情况下是NO。
6. clearsContextBeforeDrawingA Boolean value that determines whether the receiver’s bounds should be automatically cleared before drawing.
7. layerClass和 layer property 跟Core Animation layer有关
第二、管理视图层次
1. superview property 返回该view的superView
sample:
property 返回该view的subviews
sample:
- (void)viewDidLoad{ [super viewDidLoad];// Do any additional setup after loading the view, typically from a nib. UIButton *button=[[[UIButton alloc] initWithFrame:CGRectMake(120, 120, 50, 50)] autorelease]; button.backgroundColor=[UIColor redColor]; [self.view addSubview:button]; UIButton *button2=[[[UIButton alloc] initWithFrame:CGRectMake(130, 130, 50, 50)] autorelease]; button2.backgroundColor=[UIColor blueColor]; [self.view addSubview:button2]; UIButton *button3=[[[UIButton alloc] initWithFrame:CGRectMake(120, 120, 100, 100)] autorelease]; button3.backgroundColor=[UIColor greenColor]; [self.view addSubview:button3]; [self.view exchangeSubviewAtIndex:1 withSubviewAtIndex:3];}
12– isDescendantOfView:
Returns a Boolean value indicating whether the receiver is a subview of a given view or identical to that view.
- (BOOL)isDescendantOfView:(UIView *)view
sample:
NSLog(@"the result is %d",[button3isDescendantOfView:self.view]);
