How do I solve a 'NSUnknownKeyException' ... setValue:forUndefinedKey:]: ...not key value coding compliant [duplicate]
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.
The easiest way to check that is to Ctrl+Click on your Controller in the Storyboard View and look for something in the resulting popup which has a yellow warning mark next to it.Simply delete it by pressing the (x) next to the Outlet name.
If you are using a storyboard then just click on every ViewController and select the connections inspector of them. Check whether there exit any exclamatory sign(for lost connections).
Delete them properly.Then run your project again.