iOS autoresizingMask使用

/*
 UIViewAutoresizingNone                 = 0,      /// 不随父视图的改变而改变
 UIViewAutoresizingFlexibleLeftMargin   = 1 << 0, /// 自动调整view与父视图左间距，保证右间距不变
 UIViewAutoresizingFlexibleWidth        = 1 << 1, /// 自动调整view的宽度，保证左间距和右间距不变
 UIViewAutoresizingFlexibleRightMargin  = 1 << 2, /// 自动调整view与父视图右间距，以保证左间距不变
 UIViewAutoresizingFlexibleTopMargin    = 1 << 3, /// 自动调整view与父视图上间距，以保证下间距不变
 UIViewAutoresizingFlexibleHeight       = 1 << 4, /// 自动调整view的高度，以保证上间距和下间距不变
 UIViewAutoresizingFlexibleBottomMargin = 1 << 5  /// 自动调整view与父视图的下间距，以保证上间距不变
 */

测试代码如下

- (void)viewDidLoad {
    [super viewDidLoad];
    
    UIView *redView = [[UIView alloc] init];
    self.redView = redView;
    [self.view addSubview: redView];
    redView.frame = CGRectMake(100, 100, 300, 300);
    redView.backgroundColor = [UIColor redColor];
    
    UIView *blueView = [[UIView alloc] init];
    [redView addSubview:blueView];
    blueView.backgroundColor = [UIColor blueColor];
    blueView.frame = CGRectMake(50, 50, 100, 100);
    blueView.autoresizingMask = UIViewAutoresizingFlexibleBottomMargin;
    
    
    NSLog(@"%ld",self.view.autoresizingMask);
    NSLog(@"---%d",1 << 1 | 1 << 4);
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    CGRect f = self.redView.frame;
    f.size.width +=5;
    f.size.height +=5;
    self.redView.frame = f;
}