I save mp3 file into Core Data as NSData binary data. Then I load this file with help of `NSFetchedResultsController`. Then I wrote following code but I got the error. How can I fix it? 

> 
> fatal error: unexpectedly found nil while unwrapping an Optional value
> 
> 
> 

```
var audioPlayer = AVAudioPlayer()
func play() {
    if musicData != nil {
        audioPlayer = AVAudioPlayer(data: musicData, error: nil)
        AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, error: nil)
        AVAudioSession.sharedInstance().setActive(true, error: nil)
        audioPlayer.prepareToPlay()
        audioPlayer.play()
    }
}

```

**UPDATE**
I checked it and I saw that `AVAudioPlayer` is nil but I init this player in beginning of this class.

Still I changed code but I get the same error
The second method

```
var av = AVAudioPlayer()
func play() {
    let object = fetchedResultsController.fetchedObjects?.first as! Entity
    let songData = object.mp3

    var urlData: NSURL!
    songData.writeToURL(urlData, atomically: true)
    av = AVAudioPlayer(contentsOfURL: urlData, error: nil)
    av.prepareToPlay()
    av.play()
}

```