何时在iOS10 SDK中设置视框大小? [英] When is view frame size set in iOS10 SDK?

问题描述

多年来，在Swift和ObjC中，我一直使用这种技术制作圆形视图:

For several years in Swift and ObjC I've used this technique to make a circular view:

view.layer.cornerRadius = view.frame.size.width / 2
view.clipsToBounds = true

当情节提要中的UILayoutConstraints固定为宽度/高度时，将此代码放在viewDidLoad或viewWillAppear中就没有问题.内置iOS9.3SDK，可在iOS10等系统中正常运行.

When UILayoutConstraints in the Storyboard are fixed width / height there has been no problem putting this code in viewDidLoad, or in viewWillAppear. Built in iOS9.3SDK it runs fine in iOS10 etc.

iOS10SDK在Storyboard中显示的帧大小与固定大小完全不同，甚至在viewWillAppear和viewDidLayoutSubviews等中也是如此.我的选择是:

iOS10SDK shows framesize completely different to the fixed size in the Storyboard, even up to viewWillAppear, and in viewDidLayoutSubviews etc. My options are:

1)在viewDidAppear中执行此操作(糟糕的解决方案) 2)对CornerRadius进行硬编码(工作正常，但效果糟糕)

1) do this in viewDidAppear (awful solution) 2) hardcode the cornerRadius (works fine, but awful)

这看起来像是个错误(因为在控制台中至少没有警告的情况下，不得更改情节提要中设置的固定宽度/高度).是吗，或者此代码现在有其他位置? (随附测试代码的屏幕截图)

This looks like a bug (as a fixed width/height set in Storyboard should never be changed without at least a warning in the console). Is it, or is there a different place for this code now? (screenshot of test code attached)

推荐答案

在iOS 10中，我是在6月开始使用Xcode 8(当时是Beta版)后立即遇到此问题的.需要此解决方案:

In iOS 10, I met this issue right after I started to use Xcode 8 in june, when it was beta. This solution is needed:

在修改图层之前放置layoutIfNeeded():

self.view.layoutIfNeeded()

view.layer.cornerRadius = view.frame.size.width / 2
view.clipsToBounds = true

OR

将转角半径的代码放入viewDidLayoutSubviews()方法:

place the code for corner radius to viewDidLayoutSubviews() method:

override func viewDidLayoutSubviews() {

    view.layer.cornerRadius = view.frame.size.width / 2
    view.clipsToBounds = true

}

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