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

@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;

兄弟视图在数组中从后到前subviews排列。所以最顶层的视图将是：

[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，但这仅适用于视图都是层次结构中的兄弟姐妹的情况。