ios - Not Key Value Coding-Compliant -

I'm receiving this error on my app. Only once I get an error, I resume the background app. I need some help where error is false, this happens every time I get active from the background, whatever the Active View Controller is.

Exceptions to the exception due to 'NSUKKINK Exception', ending the app, reason: '[& lt; __ NSCF string 0xc063200 & gt; ValueForUndefinedKey:]: Important code coding for this class key is not compliant-feedback. '

It looks like somewhere in the stack, a non-existent key is accessed on an NSString Used to be. valueForUndefinedKey Objective - The key-value in C is part of the coding and is part of NSObject. When it can be called when valueForKey: does not work too much on any object

I think the exception is thrown most often when: < Ol>

A class is restarted with the storyboard of the XIB file and the storyboard or XIB does not.

You have a major memory problem, where you are calling a method on a demolished object and the wrong piece of memory is being reached.

This operation has a network JSON API and the method is retrieving the wrong type of object sorted by JSON (for example an NSString instead of NSDictionary).

Set up an exception breakpoint on all exceptions to Xcode Breakpoint Navigator so that you can find the exact line in your code being thrown on to NSUnknownKeyException . Press (+) to bring up the menu.