https://developer.apple.com/library/prerelease/tvos/documentation/WindowsViews/Conceptual/ViewPG_iPhoneOS/CreatingViews/CreatingViews.html#//apple_ref/doc/uid/TP40009503-CH5-SW1

Layout changes can occur whenever any of the following events happens in a view: a. The size of a view’s bounds rectangle changes. b. An interface orientation change occurs, which usually triggers a change in the root view’s bounds rectangle. c. The set of Core Animation sublayers associated with the view’s layer changes and requires layout. d. Your application forces layout to occur by calling the setNeedsLayout or layoutIfNeeded method of a view. e. Your application forces layout by calling the setNeedsLayout method of the view’s underlying layer object.

https://developer.apple.com/library/prerelease/tvos/documentation/WindowsViews/Conceptual/ViewPG_iPhoneOS/CreatingViews/CreatingViews.html#//apple_ref/doc/uid/TP40009503-CH5-SW1

Layout changes can occur whenever any of the following events happens in a view: a. The size of a view’s bounds rectangle changes. b. An interface orientation change occurs, which usually triggers a change in the root view’s bounds rectangle. c. The set of Core Animation sublayers associated with the view’s layer changes and requires layout. d. Your application forces layout to occur by calling the setNeedsLayout or layoutIfNeeded method of a view. e. Your application forces layout by calling the setNeedsLayout method of the view’s underlying layer object.

调用 (自我。视图setNeedsLayout]; in viewController使它调用viewDidLayoutSubviews

我也有一个类似的问题，但对答案不满意(或者我在网上能找到的任何答案)，所以我在实践中尝试了一下，下面是我得到的答案:

init does not cause layoutSubviews to be called (duh) addSubview: causes layoutSubviews to be called on the view being added, the view it’s being added to (target view), and all the subviews of the target view setFrame intelligently calls layoutSubviews on the view having its frame set only if the size parameter of the frame is different scrolling a UIScrollView causes layoutSubviews to be called on the scrollView, and its superview rotating a device only calls layoutSubview on the parent view (the responding viewControllers primary view) Resizing a view will call layoutSubviews on its superview (Important: views with an intrinsic content size will re-size if the content that determines their size changes; for example, updating the text on a UILabel will cause the intrinsic content size to be updated and thus call layoutSubviews on its superview)

我的结果- http://blog.logichigh.com/2011/03/16/when-does-layoutsubviews-get-called/

你看过layoutIfNeeded吗?

文档片段如下所示。如果在动画期间显式调用此方法，动画是否工作?

layoutIfNeeded 如果需要，则显示子视图。

- (void)layoutIfNeeded

讨论 使用此方法在绘制前强制子视图的布局。

可用性 支持iPhone OS 2.0及以上版本。

BadPirate回答中的一些观点只有部分正确:

For addSubView point addSubview causes layoutSubviews to be called on the view being added, the view it’s being added to (target view), and all the subviews of the target. It depends on the view's (target view) autoresize mask. If it has autoresize mask ON, layoutSubview will be called on each addSubview. If it has no autoresize mask then layoutSubview will be called only when the view's (target View) frame size changes. Example: if you created UIView programmatically (it has no autoresize mask by default), LayoutSubview will be called only when UIView frame changes not on every addSubview. It is through this technique that the performance of the application also increases. For the device rotation point Rotating a device only calls layoutSubview on the parent view (the responding viewController's primary view) This can be true only when your VC is in the VC hierarchy (root at window.rootViewController), well this is most common case. In iOS 5, if you create a VC, but it is not added into any another VC, then this VC would not get any noticed when device rotate. Therefore its view would not get noticed by calling layoutSubviews.