Getting a Swift run-time error (NSException) - swift

Question

I'm relatively new to Swift programming and I'm getting a run-time that is irking me quite a bit and I'm not sure why this is occurring as the source code looks correct.
The run-time error leads me to this in the console:
'[<UIViewController 0x7ff27051a5f0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key btnRoll.'
*** First throw call stack:
(
0 CoreFoundation 0x0000000103744e65 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x0000000105484deb objc_exception_throw + 48
2 CoreFoundation 0x0000000103744aa9 -[NSException raise] + 9
3 Foundation 0x0000000103b0d9bb -[NSObject(NSKeyValueCoding) setValue:forKey:] + 288
4 UIKit 0x00000001040f0320 -[UIViewController setValue:forKey:] + 88
5 UIKit 0x000000010431ef41 -[UIRuntimeOutletConnection connect] + 109
6 CoreFoundation 0x00000001036854a0 -[NSArray makeObjectsPerformSelector:] + 224
7 UIKit 0x000000010431d924 -[UINib instantiateWithOwner:options:] + 1864
8 UIKit 0x00000001040f6eea -[UIViewController _loadViewFromNibNamed:bundle:] + 381
9 UIKit 0x00000001040f7816 -[UIViewController loadView] + 178
10 UIKit 0x00000001040f7b74 -[UIViewController loadViewIfRequired] + 138
11 UIKit 0x00000001040f82e7 -[UIViewController view] + 27
12 UIKit 0x0000000103fceab0 -[UIWindow addRootViewControllerViewIfPossible] + 61
13 UIKit 0x0000000103fcf199 -[UIWindow _setHidden:forced:] + 282
14 UIKit 0x0000000103fe0c2e -[UIWindow makeKeyAndVisible] + 42
15 UIKit 0x0000000103f59663 -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 4131
16 UIKit 0x0000000103f5fcc6 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1760
17 UIKit 0x0000000103f5ce7b -[UIApplication workspaceDidEndTransaction:] + 188
18 FrontBoardServices 0x0000000107319754 -[FBSSerialQueue _performNext] + 192
19 FrontBoardServices 0x0000000107319ac2 -[FBSSerialQueue _performNextFromRunLoopSource] + 45
20 CoreFoundation 0x0000000103670a31 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
21 CoreFoundation 0x000000010366695c __CFRunLoopDoSources0 + 556
22 CoreFoundation 0x0000000103665e13 __CFRunLoopRun + 867
23 CoreFoundation 0x0000000103665828 CFRunLoopRunSpecific + 488
24 UIKit 0x0000000103f5c7cd -[UIApplication _run] + 402
25 UIKit 0x0000000103f61610 UIApplicationMain + 171
26 Craps 0x00000001035652dd main + 109
27 libdyld.dylib 0x0000000105f8d92d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
I only have 30 lines of code or so in the mini-game I created and I don't see why the error is coming up:
//
// ViewController.swift
// Craps
//
// Created by Lamido Tijjo on 2/11/16.
// Copyright © 2016 YauwaSarki. All rights reserved.
//
import UIKit
class CrapsViewController: UIViewController {
var rollDice1: Int = 0
var rollDice2: Int = 0
var rollTotal: Int = 0
#IBOutlet var lblRollOne: UILabel!
#IBOutlet var lblRollTwo: UILabel!
#IBOutlet var lblTotalRoll: UILabel!
#IBAction func btnRollDice(sender: AnyObject) {
rollDice1 = Int(arc4random() % 6) + 1
rollDice2 = Int(arc4random() % 6) + 1
rollTotal = rollDice1 + rollDice2
lblRollOne.text = String(rollDice1)
lblRollTwo.text = String(rollDice2)
if rollTotal != 7 || rollTotal != 11 {
lblTotalRoll.text = "Sorry you rolled a \(rollTotal), please try again!"
} else {
lblTotalRoll.text = "Congrats! you rolled a \(rollTotal), play again if you like!"
}
}
}
Can someone or some people please kindly shed some light on the situation. Thanks!

Answer 1

You have outlets defined for your view controller in a storyboard or .xib file. One of them is called "btnRoll" and was linked to the controller at some point. The matching property does not exist in code.
Possible reasons are: you deleted the code without unlinking the outlet or you have the wrong view controller defined as the view's owner.