using AVPlayer to play a time lapse within a UIView - ios

Question

I am using a custom image/video picker to pick a time lapse, once the picker view has been dismissed I want to play the time lapse within a UIView that I have put on to the view controller in interface builder. This code I have currently is below but the problem is that at the moment when a time lapse is selected it is not played.
View outlet and var's for video player
#IBOutlet var videoView: UIView!
let ipc = QBImagePickerController()
var playerItem: AVPlayerItem?
var videoPlayer: AVPlayer?
var playerLayer: AVPlayerLayer?
did finish picking assets code
func qb_imagePickerController(imagePickerController: QBImagePickerController, didFinishPickingAssets assets: [AnyObject]) {
for asset in assets as! [PHAsset] {
PHImageManager.defaultManager().requestAVAssetForVideo(asset, options: nil, resultHandler: {(avAsset: AVAsset?, audioMix: AVAudioMix?, info: [NSObject : AnyObject]?) -> Void in
self.playerItem = AVPlayerItem(asset: avAsset!)
self.videoPlayer = AVPlayer(playerItem: self.playerItem!)
self.playerLayer = AVPlayerLayer(player: self.videoPlayer)
self.playerLayer!.frame = self.videoView.bounds
})
}
self.dismissViewControllerAnimated(true, completion: { self.play() })
}
play() function code
func play(){
videoPlayer!.play()
}
unexpectedly found nil when unwrapping an optional value

Answer 1

I don't really know about the library you are using, but it appears to have completion blocks. These are ran in the background thread.
Actually there is a problem : you dismiss your view controller before the variables (player, item etc) were assigned.
Assuming you're new to Swift I'm gonna detail you how your code will behave at runtime :
• Function is called by the delegate when your user picks a photo
• View controller is dismissed, and Player starts playing
• And then your for-loop is ran and the player is assigned an item to play (too late)
What you want to achieve is assigning an item to play and then dismiss the VC. As UI code can only be ran in the foreground (Main Thread), you cannot just move the dismiss function in the completion block, but you will need to use Grand Central Dispatch to run code in the main thread once for-loop finished.
I advise you to download the Async library in GitHub, which is a wrapper around GCD (once downloaded browse to the Sources folder and drag the Async.swift file in your Xcode project).
Then you will want to edit the "did finish picking assets" function to this in order to play your video :
func qb_imagePickerController(imagePickerController: QBImagePickerController, didFinishPickingAssets assets: [AnyObject]) {
let photoAssets = assets as! [PHAsset]
PHImageManager.defaultManager().requestAVAssetForVideo(photoAssets[0], options: nil, resultHandler: {(avAsset: AVAsset?, audioMix: AVAudioMix?, info: [NSObject : AnyObject]?) -> Void in
self.playerItem = AVPlayerItem(asset: avAsset!)
self.videoPlayer = AVPlayer(playerItem: self.playerItem!)
self.playerLayer = AVPlayerLayer(player: self.videoPlayer)
self.playerLayer!.frame = self.videoView.bounds
Async.main { self.dismissViewControllerAnimated(true, completion: { self.play() }) }
})
}
BTW I removed the for-loop coz I figured out you were just willing to pick the first asset in the array. (if wrong tell me!)
Go and try this out and tell me if it works
(More on GCD here!)