I am running xcode 5.1.1 and have been trying to learn objective C / iOS development. Right now whenever I try to run my code on the emulator (I do not have an actual device atm) it comes up with a black screen. Code can be found here. Compiling and running gives me the following error: 2014-08-23 10:42:57.429 Calculator[1862:60b] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<XYZViewController 0xe436640> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key didgetPressed.' *** First throw call stack: ( 0 CoreFoundation 0x017ed1e4 __exceptionPreprocess + 180 1 libobjc.A.dylib 0x0156c8e5 objc_exception_throw + 44 2 CoreFoundation 0x0187cfe1 -[NSException raise] + 17 3 Foundation 0x0122cd9e -[NSObject(NSKeyValueCoding) setValue:forUndefinedKey:] + 282 4 Foundation 0x011991d7 _NSSetUsingKeyValueSetter + 88 5 Foundation 0x01198731 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 267 6 Foundation 0x011fab0a -[NSObject(NSKeyValueCoding) setValue:forKeyPath:] + 412 7 UIKit 0x004e31f4 -[UIRuntimeOutletConnection connect] + 106 8 libobjc.A.dylib 0x0157e7de -[NSObject performSelector:] + 62 9 CoreFoundation 0x017e876a -[NSArray makeObjectsPerformSelector:] + 314 10 UIKit 0x004e1d4d -[UINib instantiateWithOwner:options:] + 1417 11 UIKit 0x0034a6f5 -[UIViewController _loadViewFromNibNamed:bundle:] + 280 12 UIKit 0x0034ae9d -[UIViewController loadView] + 302 13 UIKit 0x0034b0d3 -[UIViewController loadViewIfRequired] + 78 14 UIKit 0x0034b5d9 -[UIViewController view] + 35 15 UIKit 0x0026b267 -[UIWindow addRootViewControllerViewIfPossible] + 66 16 UIKit 0x0026b5ef -[UIWindow _setHidden:forced:] + 312 17 UIKit 0x0026b86b -[UIWindow _orderFrontWithoutMakingKey] + 49 18 UIKit 0x002763c8 -[UIWindow makeKeyAndVisible] + 65 19 UIKit 0x00226bc0 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 2097 20 UIKit 0x0022b667 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 824 21 UIKit 0x0023ff92 -[UIApplication handleEvent:withNewEvent:] + 3517 22 UIKit 0x00240555 -[UIApplication sendEvent:] + 85 23 UIKit 0x0022d250 _UIApplicationHandleEvent + 683 24 GraphicsServices 0x037e2f02 _PurpleEventCallback + 776 25 GraphicsServices 0x037e2a0d PurpleEventCallback + 46 26 CoreFoundation 0x01768ca5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 53 27 CoreFoundation 0x017689db __CFRunLoopDoSource1 + 523 28 CoreFoundation 0x0179368c __CFRunLoopRun + 2156 29 CoreFoundation 0x017929d3 CFRunLoopRunSpecific + 467 30 CoreFoundation 0x017927eb CFRunLoopRunInMode + 123 31 UIKit 0x0022ad9c -[UIApplication _run] + 840 32 UIKit 0x0022cf9b UIApplicationMain + 1225 33 Calculator 0x00002c8d main + 141 34 libdyld.dylib 0x01e34701 start + 1 35 ??? 0x00000001 0x0 + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException (lldb) I have attempted the following things, and so far nothing has worked 1) checked the deployment info, it has the main interface set to main 2) double checked all break points to turn them off and disabled all of them through Debug-Disable Breakpoints 3) Reset Content and Settings on the iOS Simulator. 4) Checked the issue with the LLDB Debugger, however from what I have read the issue is no longer present with the 5.1.1 xcode. 5) checked the local host is still set to 127.0.0.1 Thanks! - Terryn