子视图是以栈的方式存放的,也就是说有层次的存放
addSubview:
addsubview时都是在最上面面添加
eg:
UIView *v1 = [UIView new];
v1.frame= CGRectMake(100,100,100,60);
v1.backgroundColor= [UIColor redColor];
UIView *v2 = [UIViewnew];
v2.backgroundColor= [UIColor purpleColor];
v2.frame= CGRectMake(80,120,100,60);
[self.view addSubview:v1];
[self.view addSubview:v2];
看到如下效果
insertSubview
insertSubView可以控制将view添加到指定的层
eg:
UIView *v1 = [UIView new];
v1.frame= CGRectMake(100,100,100,60);
v1.backgroundColor= [UIColor redColor];
UIView *v2 = [UIView new];
v2.backgroundColor= [UIColor purpleColor];
v2.frame= CGRectMake(80,120,100,60);
[self.view addSubview:v1];
[self.view addSubview:v2];
UIView*v3 = [UIView new];
v3.backgroundColor= [UIColor yellowColor];
v3.frame= CGRectMake(60,140,160,60);
[self.view insertSubview:v3 atIndex:3];
可以看到v3在v1跟v2之间，按照我们的打算，atIndex:3 应该是在第四层，而现在感觉不像，我们可以打印一下看下究竟：
NSLog(@"%@",self.view.subviews);
打印如下：
(
"<_UILayoutGuide: 0x7f8893602e80; frame = (0 0; 0 0); hidden = YES; layer = <CALayer: 0x60800003e220>>",
"<_UILayoutGuide: 0x7f8893609080; frame = (0 0; 0 0); hidden = YES; layer = <CALayer: 0x60800003e080>>",
"<UIView: 0x7f8893406ab0; frame = (100 100; 100 60); layer = <CALayer: 0x60000003de40>>",
"<UIView: 0x7f8893407270; frame = (60 140; 160 60); layer = <CALayer: 0x60000003dc00>>",
"<UIView: 0x7f8893407c60; frame = (80 120; 100 60); layer = <CALayer: 0x60000003de60>>"
)
可以看到v1之前，也就是self.view有两层，v1 index就是2， v2的为4，v3 插在 index:3 ，所以在v1跟v2之间。
可以看到：
[self.view addSubView:xx.view]其实就等于[self.view insertSubView:xx.view atIndex:[self.view.subViews count]];
即在最顶层添加view。
