Swift: App terminating due to uncaught exception 'NSUnknownKeyException'

Question

I'm developing a simple game and I am having trouble when a particular UIViewController (called SPSwipes.swift) is loaded. On the screen, there are three buttons: 5, 10, and 25. When one is picked, a variable is set in that scene and the player moves on to the main Game: GameScene.swift.

As far as I am aware, the variables are recognised in the GameScene, but there is a 'NSUnknownKeyException' error when I open up the SPSwipes view in the simulator. This is done by way of a segue. Here is the error in more detail:

2014-11-09 15:32:43.718 Swipe Racer[2644:1620056] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<Swipe_Racer.SPSwipes 0x7fbf52d461b0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key fiveSwipes.'
*** First throw call stack:
(
0   CoreFoundation                      0x000000010c021f35 __exceptionPreprocess + 165
1   libobjc.A.dylib                     0x000000010dd1bbb7 objc_exception_throw + 45
2   CoreFoundation                      0x000000010c021b79 -[NSException raise] + 9
3   Foundation                          0x000000010c4397b3 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 259
4   CoreFoundation                      0x000000010bf6be80 -[NSArray makeObjectsPerformSelector:] + 224
5   UIKit                               0x000000010cd28c7d -[UINib instantiateWithOwner:options:] + 1506
6   UIKit                               0x000000010cb87f98 -[UIViewController _loadViewFromNibNamed:bundle:] + 242
7   UIKit                               0x000000010cb88588 -[UIViewController loadView] + 109
8   UIKit                               0x000000010cb887f9 -[UIViewController loadViewIfRequired] + 75
9   UIKit                               0x000000010cb88c8e -[UIViewController view] + 27
10  UIKit                               0x000000010caa7ca9 -[UIWindow addRootViewControllerViewIfPossible] + 58
11  UIKit                               0x000000010caa8041 -[UIWindow _setHidden:forced:] + 247
12  UIKit                               0x000000010cab472c -[UIWindow makeKeyAndVisible] + 42
13  UIKit                               0x000000010ca5f061 -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 2628
14  UIKit                               0x000000010ca61d2c -[UIApplication _runWithMainScene:transitionContext:completion:] + 1350
15  UIKit                               0x000000010ca60bf2 -[UIApplication workspaceDidEndTransaction:] + 179
16  FrontBoardServices                  0x000000011383b2a3 __31-[FBSSerialQueue performAsync:]_block_invoke + 16
17  CoreFoundation                      0x000000010bf5753c __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
18  CoreFoundation                      0x000000010bf4d285 __CFRunLoopDoBlocks + 341
19  CoreFoundation                      0x000000010bf4d045 __CFRunLoopRun + 2389
20  CoreFoundation                      0x000000010bf4c486 CFRunLoopRunSpecific + 470
21  UIKit                               0x000000010ca60669 -[UIApplication _run] + 413
22  UIKit                               0x000000010ca63420 UIApplicationMain + 1282
23  Swipe Racer                         0x000000010be380de top_level_code + 78
24  Swipe Racer                         0x000000010be3811a main + 42
25  libdyld.dylib                       0x000000010e507145 start + 1
26  ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

As you can see, there is an issue with my first variable, fiveSwipes (and I would imagine that there would be errors with the two others). What does 'this class is not key value coding-compliant for the key fiveSwipes' mean? How should I go about fixing it?

My SPSwipes.swift file:

class SPSwipes: UIViewController {

var no_of_swipes = 0

@IBAction func fiveSwipes(sender: AnyObject) {
    no_of_swipes = 5

//and so on

}

Thank you in advance,

Will

Answer 1

This is an old question, the other answers din't help to fix my issue so would like to leave this answer here might help other people.

Our app contains multiple "Targets" now it happens that the ViewController is pointing to specific target and only on that target this ViewController works. When running on other target the app crashes with this error.

So, for those who has multiple "Targets" be sure to check the "Module" in the "Identity Inspector" and make sure that the "Inherit Module From Target" is checked.

Answer 2

For me it was because I had multiple views connected to non existent IBOutlets

To get an idea how to find out:

1- Click on the whole view controller

2- go to : Show the connector Inspector

There you will find all the not connected outlets

Answer 3

Another possible reason for this is if you are initializing your Controller using nibName:bundle: and you pass it the wrong nib name - some other nib that is not for this controller. The end result is the same, you'll likely have a bunch of @IBOutlets that do not match up between the Controller and the nib.

Answer 4

The problem was that the button was linked to numerous IBActions - three of which didn't exist. I right clicked on the button in the Interface Builder and removed the old and irrelevant links, fixing the problem.

Answer 5

The exception is happening when attempting to load the view based on what you set up in Interface Builder. It's looking for fiveSwipes and not finding it. This can happen if you edited your code and forgot to update a connection in IB.

Have you made a connection in IB to something called fiveSwipes that isn't this function? Perhaps a variable called fiveSwipes? The way to fix the problem would be to find the element with the bad connection in IB and clear that connection.