UIView 兄弟姐妹按添加到其父视图的顺序堆叠.UIView 层次结构方法和属性用于管理视图顺序.在 UIView.h 中:

UIView siblings are stacked in the order in which they are added to their superview. The UIView hierarchy methods and properties are there to manage view order. In UIView.h:

@property(nonatomic,readonly) UIView *superview;
@property(nonatomic,readonly,copy) NSArray *subviews;

- (void)removeFromSuperview;
- (void)insertSubview:(UIView *)view atIndex:(NSInteger)index;
- (void)exchangeSubviewAtIndex:(NSInteger)index1 withSubviewAtIndex:(NSInteger)index2;

- (void)addSubview:(UIView *)view;
- (void)insertSubview:(UIView *)view belowSubview:(UIView *)siblingSubview;
- (void)insertSubview:(UIView *)view aboveSubview:(UIView *)siblingSubview;

- (void)bringSubviewToFront:(UIView *)view;
- (void)sendSubviewToBack:(UIView *)view;

兄弟视图在 subviews 数组中从前到后排序.所以最上面的视图将是:

The sibling views are ordered back to front in the subviews array. So the topmost view will be:

[parentView.subviews lastObject];

底部视图将是:

[parentView.subviews objectAtIndex:0];

就像 Kolin Krewinkel 所说的那样，[parentView BringSubviewToFront:view] 会将视图带到顶部，但只有当视图在层次结构中都是兄弟时才会出现这种情况.

Like Kolin Krewinkel said, [parentView bringSubviewToFront:view] will bring the view to the top, but this is only the case if the views are all siblings in the hierarchy.