uiview 的方法
//定義3個view
UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
view1.backgroundColor = [UIColor redColor];
[self.window addSubview:view1];
UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(120, 150, 100, 100)];
view2.backgroundColor = [UIColor yellowColor];
[self.window addSubview:view2];
UIView *view3 = [[UIView alloc] initWithFrame:CGRectMake(140, 200, 100, 100)];
view3.backgroundColor = [UIColor greenColor];
[self.window addSubview:view3];
//UIView添加視圖的方法
//1.在指定的Index處插入子視圖
[self.window insertSubview:view2 atIndex:0];
//2.在指定的視圖上面添加子視圖
[self.window insertSubview:view1 aboveSubview:view2];
//3.在指定的視圖下⾯面添加⼦子視圖
[self.window insertSubview:view3 belowSubview:view2];
//UIview 管理視圖層次
//1.把指定的視圖移動到最前面
[self.window bringSubviewToFront:view1];
//2.把指定的子視圖移動到最後面
[self.window sendSubviewToBack:view2];
//3.交換兩個指定索引位置子視圖
[self.window exchangeSubviewAtIndex:0 withSubviewAtIndex:1];
//4.刪除某個子視圖
[view3 removeFromSuperview];
//UIView 視圖屬性
//1.hidden控制視圖的顯隱
view1.hidden = YES;
//2.alpha控制視圖的透明度(0-1)
view1.alpha = 0.5;
//3.superview 獲取本視圖的父視圖
UIView * superView = [view1 superview];
//調用父視圖改變屬性
superView.backgroundColor = [UIColor yellowColor];
//4.subviews 獲取本視圖的所有子視圖 他取出來是以數組形式存放
NSArray * subview = [self.window subviews];
//調用子視圖改變屬性
((UIView*)subview[0]).backgroundColor = [UIColor grayColor];
//5.tag 給視圖添加標記,被加完標記的視圖可以使用viewWithTag:方法取出
view1.tag = 101;
UIView *view = [self.window viewWithTag:101];
view.alpha = 0.1;