传入呼叫发生时的约束错误（UITextEffectsWindow - UIInputSetContainerView - ...）

Question

当来电发生时，我在我的项目中遇到以下消息......

---------------在调试区开始记录消息---------------

2015-11-12 18:19:16.707 test[75925:6804554] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSLayoutConstraint:0x7fafbacbeba0 V:|-(20)-[UIInputSetContainerView:0x7fafbacbca20]   (Names: '|':UITextEffectsWindow:0x7fafbac12b20 )>",
    "<NSLayoutConstraint:0x7fafbac04390 'UIInputWindowController-top' V:|-(0)-[UIInputSetContainerView:0x7fafbacbca20]   (Names: '|':UITextEffectsWindow:0x7fafbac12b20 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7fafbacbeba0 V:|-(20)-[UIInputSetContainerView:0x7fafbacbca20]   (Names: '|':UITextEffectsWindow:0x7fafbac12b20 )>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

---------------调试区内的结束日志消息---------------

因此，我决定逐步解构我的视图，直到此消息消失以确定哪个约束负责。我一无所获。

实际上，它也发生在一个几乎空的项目中。

例如：

1. 创建一个新的＆＃34;单一视图应用程序＆＃34;
2. 在Interface Builder中选择Viewcontroller
3. 编辑器＆gt;嵌入＆gt;导航控制器
4. 构建并运行
5. 在模拟器中：硬件＆gt;切换通话中状态栏（cmd Y）

你看到了同样的问题。

这是来自XCode的错误还是我错过了什么？ （我使用这个XCode 7.0.1）

我该怎么办？

事先，谢谢你的答案。