'NSUnknownKeyException' … setValue:forUndefinedKey:]: …not key value coding compliant

解决一个问题：

当我添加一个IBout，

  报了如下错误

NSUnknownKeyException' … setValue:forUndefinedKey:]: …not key value coding compliant

一般情况下是

 

      Look in your storyboard or xib (whichever you're using) for the ViewControllerWelcome object. The most likely source of this error is that something has a connection to an action or outlet called done that doesn't exist in the code for that class.

　　查看你得storyboard or xib 。。最大的可能是有一个connection to an action or outlet 在相应地类中没有对应的代码。