Thread in my project, how can I fix it?

2016-01-04 20:53:56.024 FunFact[78261:4841618] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<FunFact.ViewController 0x7fbc98d3a160> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key randomNumber.' *** First throw call stack: ( 0 CoreFoundation 0x000000010ac53e65 exceptionPreprocess + 165 1 libobjc.A.dylib 0x000000010c993deb objc_exception_throw + 48 2 CoreFoundation 0x000000010ac53aa9 -[NSException raise] + 9 3 Foundation 0x000000010b01c9bb -[NSObject(NSKeyValueCoding) setValue:forKey:] + 288 4 UIKit 0x000000010b5ff320 -[UIViewController setValue:forKey:] + 88 5 UIKit 0x000000010b82df41 -[UIRuntimeOutletConnection connect] + 109 6 CoreFoundation 0x000000010ab944a0 -[NSArray makeObjectsPerformSelector:] + 224 7 UIKit 0x000000010b82c924 -[UINib instantiateWithOwner:options:] + 1864 8 UIKit 0x000000010b605eea -[UIViewController _loadViewFromNibNamed:bundle:] + 381 9 UIKit 0x000000010b606816 -[UIViewController loadView] + 178 10 UIKit 0x000000010b606b74 -[UIViewController loadViewIfRequired] + 138 11 UIKit 0x000000010b6072e7 -[UIViewController view] + 27 12 UIKit 0x000000010b4ddab0 -[UIWindow addRootViewControllerViewIfPossible] + 61 13 UIKit 0x000000010b4de199 -[UIWindow _setHidden:forced:] + 282 14 UIKit 0x000000010b4efc2e -[UIWindow makeKeyAndVisible] + 42 15 UIKit 0x000000010b468663 -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 4131 16 UIKit 0x000000010b46ecc6 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1760 17 UIKit 0x000000010b46be7b -[UIApplication workspaceDidEndTransaction:] + 188 18 FrontBoardServices 0x000000010e828754 -[FBSSerialQueue _performNext] + 192 19 FrontBoardServices 0x000000010e828ac2 -[FBSSerialQueue _performNextFromRunLoopSource] + 45 20 CoreFoundation 0x000000010ab7fa31 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 17 21 CoreFoundation 0x000000010ab7595c __CFRunLoopDoSources0 + 556 22 CoreFoundation 0x000000010ab74e13 __CFRunLoopRun + 867 23 CoreFoundation 0x000000010ab74828 CFRunLoopRunSpecific + 488 24 UIKit 0x000000010b46b7cd -[UIApplication _run] + 402 25 UIKit 0x000000010b470610 UIApplicationMain + 171 26 FunFact 0x000000010aa73bfd main + 109 27 libdyld.dylib 0x000000010d49c92d start + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException

(lldb)

This is what happens when I try to start my app on simulator. Anyone knows what this means or how I can fix this issue. It has something to do with app delegate, I think, which I have not touched.