How do I get a mediaItemCollection from the mediaPickerController to play on an AVPlayer?

In my quest to answer this question I came across this in a book.

"MPMediaItem, however, has an MPMediaItemPropertyAssetURL key (or assetURL property) whose value is a URL. That gives you a reference to the music file on disk,...having obtained an MPMediaItem’s asset URL, you could use that URL to initialize an AVAudioPlayer, an AVPlayer, or an AVAsset."

So I tried to use the mediaPickerController to get the asset url like this.

    func mediaPicker(mediaPicker: MPMediaPickerController, didPickMediaItems mediaItemCollection: MPMediaItemCollection) {

    guard let mediaItem = mediaItemCollection.items.first else {
        NSLog("No item selected.")
        return
    }
    var songURL = mediaItem.valueForProperty(MPMediaItemPropertyAssetURL) as! NSURL
    print(songURL)
    self.dismissViewControllerAnimated(true, completion: nil)
}

In the book it gives this as an example:

let arr = // array of MPMediaItem
let items = arr.map {
    let url = $0.assetURL!
    let asset = AVAsset(URL:url)
    return AVPlayerItem(asset: asset)
}
self.qp = AVQueuePlayer(items:items)
self.qp.play()

Im not sure how to get the mediaItemCollection to the arr variable. The use of songURL and MediaItemCollection are inside the picker mediaPicker function. I can't access it outside of it's function. How do I get this to work?

OK. I figured this out.

The solution is to declare the variable outside of the function first, but under the class. I just created it like this:

class ViewController: UIViewController, MPMediaPickerControllerDelegate {

var songUrl: NSURL = NSURL()
var player = AVPlayer()


func mediaPicker(mediaPicker: MPMediaPickerController, didPickMediaItems mediaItemCollection: MPMediaItemCollection) {

    guard let mediaItem = mediaItemCollection.items.first else {
        NSLog("No item selected.")
        return
    }
    songUrl = mediaItem.valueForProperty(MPMediaItemPropertyAssetURL) as! NSURL
    print(songUrl)

    self.dismissViewControllerAnimated(true, completion: nil)
}

Now I can access the songUrl outside of the function.