iOS AutoLayout - 获取帧大小宽度

问题描述

我正在使用 iOS 6 自动布局进行开发

I am developing using iOS 6 auto layout

我想记录一条显示视图框架宽度的消息.

I would like to log a message displaying the frame width of the view.

我可以在屏幕上看到 textView.

I can see the textView on the screen.

但我得到的宽度和高度为零，我错过了什么吗?

But I get the width and height as zero, am I missing something ?

NSLog(@"textView    = %p", self.textView);
NSLog(@"height      = %f", self.textView.frame.size.height);
NSLog(@"width       = %f", self.textView.frame.size.width);

textView    = 0x882de00
height      = 0.000000
width       = 0.000000

推荐答案

我认为自动布局在你调用它的时候还没有时间来布局你的视图.在调用 viewDidLoad 时自动布局还没有发生，因为它是在视图加载后调用的，并且只有在视图被放置到视图控制器的视图层次结构中并最终布局之后(在视图的 layoutSubviews 方法中).

I think auto layout hasn't had the time to layout your views by the time you call this. Auto layout hasn't happened by the time viewDidLoad is called, because it's called just after the views are loaded and it's only after that that the views are placed into the view controller's view hierarchy and eventually laid out (in the view's layoutSubviews method).

这个答案指出了为什么问题中的场景不起作用.@dreamzor 的回答指出了将代码放置在何处以解决问题.

this answer points out why the scenario in the question doesn't work. @dreamzor's answer points out where to place your code in order to solve it.

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