问题描述
我有一个 UIPageViewController 的子类，并在其 viewDidLoad中我要添加的UILabel 到 self.view 。这工作得很好，如果我设置使用框架的地位，但如果我尝试使用自动布局来定位它，我得到：
I have a UIPageViewController subclass, and in its viewDidLoad I want to add a UILabel to its self.view. This works fine if I set its position using frames, but if I try to position it using Auto Layout, I get:
的 * 的中断言失败 - [_ UIPageViewControllerContentView layoutSublayersOfLayer：]，/SourceCache/UIKit_Sim/UIKit-2935.58/UIView.m:8742
我应该怎么定位这个中的UILabel显示了 UIPageViewController ？
How am I supposed to position this UILabel to show up in the UIPageViewController?
推荐答案
这似乎发生，因为 UIPageViewController 的观点（这实际上是一个如预期（至少在iOS的7 _UIPageViewControllerContentView ）不处理子视图和自动布局;它的iOS 8）工作对我罚款
This seems to be happening because UIPageViewController's view (which is actually a _UIPageViewControllerContentView) doesn't handle subviews and autolayout as expected (at least in iOS 7; it worked fine for me in iOS 8).
您可以通过不使用自动布局解决这个问题，但我想用自动布局，所以我结束了重做我的视图控制器，以避免增加子视图 UIPageViewController 。
You can get around this by not using autolayout, but I wanted to use autolayout so I ended up redoing my view controllers to avoid adding subviews to UIPageViewController.
而不是子类化 UIPageViewController ，我创建了一个容器视图控制器（子类的UIViewController ）以 UIPageViewController 作为一个子视图控制器。那时，我最初曾在 UIPageViewController 自定义子视图被添加到容器的视图。我还做了容器中的数据源和委托的 UIPageViewController 。
Instead of subclassing UIPageViewController, I created a container view controller (a subclass of UIViewController) with a UIPageViewController as a child view controller. The custom subviews that I initially had in UIPageViewController were then added to the container's view. I also made the container the data source and delegate for the UIPageViewController.
有一个相关话题，人们得到了相同的断言失败，但与的UITableViewCell ："Auto布局执行-layoutSubviews＆QUOT后仍然需要;用的UITableViewCell子类。大部分的建议有没有工作或不适用UIPageViewController，但它帮助我弄清楚为什么添加子视图与自动布局可能会导致问题。
There's a related thread where people got the same assertion failure but with a UITableViewCell: "Auto Layout still required after executing -layoutSubviews" with UITableViewCell subclass. Most of the suggestions there don't work or aren't applicable to UIPageViewController, but it helped me figure out why adding subviews with autolayout might cause a problem.
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