SWIFT fatal error: unexpectedly found nil while unwrapping an Optional value (lldb)

Question

i'm trying to run this swift code but it outputs the following error: "fatal error: unexpectedly found nil while unwrapping an Optional value (lldb)". This is the code:

 //
//  PlaySoundsViewController.swift
//  Revoice
//
//  Created by Leonardo Barazza on 16/04/15.
//  Copyright (c) 2015 Leonardo Barazza. All rights reserved.
//

import UIKit
import AVFoundation

class PlaySoundsViewController: UIViewController {

    var audioPlayer: AVAudioPlayer!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        if var filePath = NSBundle.mainBundle().pathForResource("movie_quote", ofType: "mp3") {
            var filePathUrl = NSURL.fileURLWithPath(filePath)
            audioPlayer = AVAudioPlayer(contentsOfURL: filePathUrl, error: nil)
        } else {
            println("the filePath is empty")
        }
    }

    @IBAction func playSlowly(sender: UIButton) {
        audioPlayer.play()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}

Can you help me?

Thanks in advance.

you may want to give more information where exactly the debugger breaks. and gives you the error. In general, a nil is given where your code expected a non nil. — Volker, Apr 19 '15 at 14:00
Do not explicitly unwrap things that can ever, under any circumstances be nil–unless you want crashes. — zaph, Apr 19 '15 at 14:44
possible duplicate of [fatal error: unexpectedly found nil while unwrapping an Optional value](http://stackoverflow.com/questions/24948302/fatal-error-unexpectedly-found-nil-while-unwrapping-an-optional-value) — GoZoner, Apr 19 '15 at 16:03

user2340612 · Accepted Answer · 2015-04-19T14:24:11.303

I guess the problem is in audioPlayer property: it's defined as an implicitly unwrapped AVAudioPlayer optional, so it cannot be nil whenever you access it (otherwise a runtime exception is thrown, because of the implicitly unwrap).

The problem is that you actually create an instance (audioPlayer != nil) only if filePath != nil. Did you check that filePath is not nil?

By the way you can skip this problem by using optional chaining:

@IBAction func playSlowly(sender: UIButton) {
    if audioPlayer?.play() == nil {
        println("audioPlayer is nil")
    }
}

Yichen Zhou · Answer 2 · 2015-04-19T14:30:02.433

From your code above the question, you created only one instance variable, audioPlayer: AVAudioPlayer , with excalmatory mark !.

The error will show when the complier use the instance which was not created yet.
After read your code, only one place used the instance of AVAudioPlayer, func playSlowly(). But you did not show your debugger information, I can just guess audioPlayer.play() is the place where the error is.
I think the code if var filePath = NSBundle.mainBundle().pathForResource("movie_quote", ofType: "mp3") , leads to the failing to define the instance of audioPlayer.
You should check whether the definition of filePath is correct.

SWIFT fatal error: unexpectedly found nil while unwrapping an Optional value (lldb)

2 Answers2