在我的例子中，我删除了一个名为“viewController”的类，没有意识到它是用故事板的身份检查器选中的(在顶部的“自定义类”下)。

你只需要在你的身份检查器的自定义类字段中为视图控制器选择正确的类，或者添加一个新类到你的项目中，并选择它作为你的自定义类。

为我工作!

转到构建阶段->编译源代码并添加新的。m文件。

只需在appdelegate applicatoindidfinishlanching方法的开头添加以下代码，就可以正常工作了

(myclass类);

在我的例子中，问题是一个死的IBOutlet链接。一旦这个问题解决了，一切又恢复了正常。

I tried most of the solutions you guys suggested above but to no avail. After reading the solution from user776904's I suspected I was having the same issue as I had rebuilt my app from the ground up but copied the xib files from the previous project. I suspected the xib file had a reference to the old project that was causing my error so I simply deleted my mainwindow_ipad.xib file and copied in a new one from a clean new project. This solved it. And I was not game enough to start changing bits of the xib file in its source code.

删除错误的最好方法是: 1)选择类文件(.m) 2)在“目标会员”下，“勾选”项目名称条目