setNeedsLayout 和 setNeedsDisplay [英] setNeedsLayout and setNeedsDisplay

问题描述

UIView 方法 setNeedsLayout 和 setNeedsDisplay 之间的真正区别是什么?

What is the real difference between UIView methods setNeedsLayout and setNeedsDisplay?

像往常一样，文档对此很模糊.

As usual documentation is foggy about this.

推荐答案

实际上文档对此非常清楚:

Actually the documentation is pretty clear about this:

• setNeedsLayout 将布局子视图

当你想调整一个视图的子视图的布局时，在你的应用程序的主线程上调用这个方法.

Call this method on your application’s main thread when you want to adjust the layout of a view’s subviews.

setNeedsDisplay 将要求重绘您的视图(drawRect: 等).

setNeedsDisplay will call for a redraw of your view (drawRect:, etc).

您可以使用此方法或 setNeedsDisplayInRect: 通知系统您的视图内容需要重绘.

You can use this method or the setNeedsDisplayInRect: to notify the system that your view’s contents need to be redrawn.

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