为什么叫viewdidlayoutsubviews多次？ [英] Why viewdidlayoutsubviews call multiple times?

问题描述

我对雨燕的iOS开发通用应用程序，使用自动布局和仅支持肖像。

I'm developing iOS Universal App on Swift,using auto layout and support only portrait.

我发现的UIViewController＃viewdidlayoutsubviews 多次调用。相反， viewDidLoad中仅在启动MyApp的的UIViewController调用一次。

I found UIViewController#viewdidlayoutsubviews called multiple times. Instead, viewDidLoad ONLY call once on starting up MyApp's UIViewController.

为什么viewdidlayoutsubviews多次调用？每个UIView的约束（UIButtons，UITextFields等）会按顺序执行？

Why viewdidlayoutsubviews call multiple times? Constraints on each UIView(UIButtons,UITextFields etc..) will perform in order?

任何信息将AP preciated。

Any Information will be appreciated.

推荐答案

的loadView 只能称为一种：当视图需要加载

LoadView is only called one: when the view needs to be loaded.

LayoutSubviews ，但是，每次运行循环调用一次上有过任何视图 setNeedsLayout 或 setNeedsDisplayInRect 调用它 - 这包括每当一个子视图已被添加到视图，滚动，缩放，等

LayoutSubviews, however, is called once per run loop on any view that has had setNeedsLayout or setNeedsDisplayInRect called on it - this includes whenever a subview has been added to the view, scrolling, resizing, etc.

请参阅此链接了解更多信息。它使用Objective-C的，但信息仍然有效。

See this link for more information. It uses Objective-C, but the information still holds.

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