Why am I getting NSUnknownKeyException in setValue:forUndefinedKey:?

Question

I am making a small iOS application that tracks the amount of time that I have clocked in at work. I am very new to Swift and Xcode, so this is being a challenge for me. Details: I am using Xcode 7, the target development is 8.3. I believe I am missing something small like a class file. The app crashes on start up.

Error:

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key ButtonIn.'

Code:

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.



    }
    @IBOutlet weak var Lb1: UILabel!

    @IBAction func ButtonIn(sender: AnyObject) {
        self.Lb1.text = "Clocked In!"
    }

    @IBAction func ButtonOut(sender: AnyObject) {
        self.Lb1.text = "Clocked Out!"
    }
}

Check the xib associated with this view controller. Search in xCode for "ButtonIn". You should find it there. — ajmccall, Sep 21 '15 at 16:31
Yeah, looks like you have something setup wrong in the storyboard. Can you post screenshots of how you wired up the outlets and actions? — i_am_jorf, Sep 21 '15 at 16:32
In addition, this is a very low quality question. The title is redundant. Please view SO guidelines otherwise you will not attract answers and your question will be down voted. http://stackoverflow.com/help/how-to-ask — ajmccall, Sep 21 '15 at 16:32
Everything seems to be okay with your class afaik (except for conventions like methods beginning with small letters), so the issue is probably lying somewhere else. — Jeehut, Sep 21 '15 at 16:38
I added screenshots, I do apologize for the low quality question, I am new. — Jacob Eggebeen, Sep 21 '15 at 17:35

Dharmesh Siddhpura · Answer 1 · 2015-09-22T11:27:51.800

1

This happens usually when the bind outlet is changed. Follow below mentioned steps:

Go to .xib file or storyboard scene for the class having this issue.
Select "File's Owner"
Select "Show the Connection Inspector" on the right panel
If you find any exclamation mark on ButtonIn connection then re-bind it.

Hope this helps.

edited Sep 22 '15 at 11:27

answered Sep 21 '15 at 17:05

Dharmesh Siddhpura

1,610
12
22

I do not see any .xib files.. – Jacob Eggebeen Sep 21 '15 at 17:15
In your Xcode's project navigator you can see .xib file for ViewController class. If not then you might be using storyboard. If so then select your view controller in storyboard and follow above steps. – Dharmesh Siddhpura Sep 21 '15 at 17:21
I hate to say it, but I can not find where the "File Owner" is. – Jacob Eggebeen Sep 21 '15 at 17:36
Its alright. In your case (first screenshot) "ViewController" scene is your file owner. Select that and check connection inspector. – Dharmesh Siddhpura Sep 21 '15 at 17:44
I don't see any problems.. – Jacob Eggebeen Sep 21 '15 at 18:12
Yes there is a problem my friend. Your outlets are not bound properly. Thats what I was talking about. The '!' (exclamation) type of icon. I did some marking & text on the third screenshot which you had uploaded and re-uploaded it in my answer. Try to remove those 3 bindings and run the app first, you can see there will be no crash and then re-bind it. – Dharmesh Siddhpura Sep 22 '15 at 02:17
Issues Solved! Thank you!! – Jacob Eggebeen Sep 22 '15 at 16:15

Why am I getting NSUnknownKeyException in setValue:forUndefinedKey:?

1 Answers1