viewController 各个life cycle阶段，view和 subviews 的frame 状态分析

视图生命周期与UIScrollView交互详解

最新推荐文章于 2025-07-10 19:42:25 发布

原创最新推荐文章于 2025-07-10 19:42:25 发布 · 3.8k 阅读

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本文详细解析了iOS中视图加载、显示与隐藏过程中的关键事件，着重讨论了viewDidLoad、viewWillAppear与viewDidAppear方法的区别及作用，并通过实例展示了如何通过按钮操作改变UIScrollView的contentOffset，以及超出bounds范围子视图的不可交互特性。

2013-03-27 17:04:40.605 testView[4685:c07] --- viewDidLoad.. ---

2013-03-27 17:04:40.608 testView[4685:c07] <UIView: 0x7553320; frame = (0 20; 320 460); autoresize = RM+BM; layer = <CALayer: 0x7553380>>

2013-03-27 17:04:40.609 testView[4685:c07] <UIScrollView: 0x7551890; frame = (0 0; 0 0); clipsToBounds = YES; autoresize = TM+BM; gestureRecognizers = <NSArray: 0x75528a0>; layer = <CALayer: 0x7551ab0>; contentOffset: {0, 0}>

2013-03-27 17:04:40.610 testView[4685:c07] <UIScrollView: 0x7551890; frame = (0 0; 0 0); clipsToBounds = YES; autoresize = TM+BM; gestureRecognizers = <NSArray: 0x75528a0>; layer = <CALayer: 0x7551ab0>; contentOffset: {0, 0}>

2013-03-27 17:04:40.613 testView[4685:c07] view bounds-origin: 0.00 0.00 size:320.00 460.00

2013-03-27 17:04:40.614 testView[4685:c07] bounds-origin: 0.00 0.00 size:0.00 0.00

viewDidLoad 的时候，self.view 和subview 的frame 未完成初始化，所以它们的frame 都是0，0，0，0

2013-03-27 17:04:40.615 testView[4685:c07] --- viewWillAppear.. ---

2013-03-27 17:16:18.755 testView[4745:c07] <UIView: 0x7557620; frame = (0 20; 320 460); autoresize = RM+BM; layer = <CALayer: 0x7557680>>

2013-03-27 17:16:18.756 testView[4745:c07] <UIScrollView: 0x7555b90; frame = (0 0; 0 0); clipsToBounds = YES; autoresize = TM+BM; gestureRecognizers = <NSArray: 0x7556ba0>; layer = <CALayer: 0x7555db0>; contentOffset: {0, 0}>

2013-03-27 17:04:40.618 testView[4685:c07] view bounds-origin: 0.00 0.00 size:320.00 460.00

2013-03-27 17:04:40.620 testView[4685:c07] scrollview bounds-origin: 0.00 0.00 size:0.00 0.00

viewWillAppear 的时候，self.view 保证完成初始化，但是subview 的frame 未完成初始化，所以view的frame size 是 size:320.00 460.00 ，但是subview 仍然是 0，0

2013-03-27 17:04:40.633 testView[4685:c07] --- viewDidAppear.. ---

2013-03-27 17:16:18.773 testView[4745:c07] <UIView: 0x7557620; frame = (0 20; 320 460); autoresize = RM+BM; layer = <CALayer: 0x7557680>>

2013-03-27 17:16:18.775 testView[4745:c07] <UIScrollView: 0x7555b90; frame = (0 0; 320 460); clipsToBounds = YES; autoresize = TM+BM; gestureRecognizers = <NSArray: 0x7556ba0>; layer = <CALayer: 0x7555db0>; contentOffset: {0, 0}>

2013-03-27 17:04:40.637 testView[4685:c07] view bounds-origin: 0.00 0.00 size:320.00 460.00

2013-03-27 17:04:40.639 testView[4685:c07] scrollview bounds-origin: 0.00 0.00 size:320.00 460.00

viewDidAppear 的时候，subview 也终于完成初始化

然后通过一个按钮，我让scrollview 的contentOffset 偏移了 (0,-50)

2013-03-27 17:04:48.304 testView[4685:c07] --- moved.. ---

2013-03-27 17:19:30.464 testView[4774:c07] --- moved.. ---

2013-03-27 17:19:30.465 testView[4774:c07] <UIView: 0x75b3d80; frame = (0 20; 320 460); autoresize = RM+BM; layer = <CALayer: 0x75b3de0>>

2013-03-27 17:19:30.465 testView[4774:c07] <UIScrollView: 0x75b22f0; frame = (0 0; 320 460); clipsToBounds = YES; autoresize = TM+BM; gestureRecognizers = <NSArray: 0x75b3300>; layer = <CALayer: 0x75b2510>; contentOffset: {0, -50}>

2013-03-27 17:19:30.467 testView[4774:c07] view bounds-origin: 0.00 0.00 size:320.00 460.00

2013-03-27 17:19:30.468 testView[4774:c07] bounds-origin: 0.00 -50.00 size:320.00 460.00

留意到偏移了之后，scrollview除了 contentOffset 改变了， bounds的坐标也一样改变。

－－－－－

如果你尝试过，把某个view中的一个subview的坐标改到负值，例如（－100，－50）

这样subview 的位置frame是超出了view 的bounds的。

这时候，假设subview其实是个Button，即便Button是可视的，肉眼可见，也是enable状态，你也按不到它。

似乎iOS上，超出bounds 范围的subview 是认为不可交互的。