15.UIView

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创建UIView

    // UIView view1
    UIView *view1 = [[UIView alloc] init];
    view1.frame = CGRectMake(10, 54, 350, 712);
    view1.backgroundColor = [UIColor redColor];
    [self.view addSubview:view1];
    
    NSLog(@"w:%f h:%f",[[UIScreen mainScreen] bounds].size.width,[[UIScreen mainScreen] bounds].size.height);

    
    // UIView view2
    UIView *view2 = [[UIView alloc] init];
    view2.frame = CGRectMake(10, 100, 300, 30);
    view2.backgroundColor = [UIColor blackColor];
    view2.tag = 2;  // 唯一标识
    [view1 addSubview:view2];
    
    // UIView view3
    UIView *view3 = [[UIView alloc] init];
    view3.frame = CGRectMake(20, 50, 100, 100);
    view3.backgroundColor = [UIColor purpleColor];
    view3.tag = 3;  // 唯一标识
    [view1 addSubview:view3];

父视图与子视图

    // superview
    UIView *superview = view1.superview;
    superview.backgroundColor = [UIColor grayColor];
    
    // subviews
    NSArray *subviewsArray = view1.subviews;
    for (UIView *view in subviewsArray) {
        if (view.tag == 2) {
            view.backgroundColor = [UIColor whiteColor];
        }
    }
    
    UIView *subView = [view1 viewWithTag:3];
    subView.backgroundColor = [UIColor blueColor];

层级的处理

1. 同一个父视图中后加入的View在上方
2. 子视图跟随父视图进行层级遮挡

    // 交换两个层的视图
    [view1 exchangeSubviewAtIndex:0 withSubviewAtIndex:1];
    // 插入一个视图到指定层
    UIView *view5 = [[UIView alloc] init];
    view5.frame = CGRectMake(7, 80, 200, 200);
    view5.backgroundColor = [UIColor greenColor];
    [view1 insertSubview:view5 atIndex:1];
    // 将一个View放入最上层或最下层
    [view1 bringSubviewToFront:view3];
    [view1 sendSubviewToBack:view3];

自适应

    // 自适应
    UIView *backView = [[UIView alloc] init];
    backView.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-25, 400, 50, 50);
    backView.backgroundColor = [UIColor yellowColor];
    backView.autoresizesSubviews = YES;  // 允许子视图自适应
    backView.tag = 1001;
    [self.view addSubview:backView];
    
    UIView *topView = [[UIView alloc] init];
    topView.frame = CGRectMake(10, 10, 30, 30);
    topView.backgroundColor = [UIColor purpleColor];
//    topView.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin;
    topView.autoresizingMask = UIViewAutoresizingFlexibleRightMargin;
    [backView addSubview:topView];