Photos framework and reusable UICollectionViewCell

I have a

UICollectionView

to display photos from a device's album with the

Photos

framework. The photos are correctly displayed, but if I scroll fast (like when you tape at the top of the screen to go to the top of the collectionView), I have some photos which are not at the good indexPath. I just need to scroll a bit to put the bad photo out of the screen, and everything go back in place.

I clean the cell during

prepareForReuse

by canceling the current request.

I presume it's a problem with the asynchronous request of

PHImageManager

, but I don't know how to avoid this problem. And I want to keet the asynchronous request to keep the collectionView smooth.

Here some code :

View Controller

     extension AlbumDetailViewController : UICollectionViewDataSource {
        func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
            return 1
        }
      
        func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
            return photoList.count
        }
      
        func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
  
            let cell = collectionView.dequeueReusableCellWithReuseIdentifier("PhotoCell", forIndexPath: indexPath) as! PhotoCollectionCell
  
            cell.setImage(photoList.objectAtIndex(indexPath.row) as! PHAsset)
          
            return cell
        }
    }

Custom CollectionViewCell

     class PhotoCollectionCell: UICollectionViewCell {
   
        @IBOutlet weak var imageView: UIImageView!
       
        var requestId: PHImageRequestID!
        let manager = PHImageManager.defaultManager()
       
        override func awakeFromNib() {
            super.awakeFromNib()
            // Initialization code
        }
       
        override func prepareForReuse() {
            self.imageView.image = nil
           
            manager.cancelImageRequest(self.requestId)
        }
       
        func setImage(asset: PHAsset) {
           
            let option = PHImageRequestOptions()
           
            option.resizeMode = .Fast
            option.deliveryMode = .HighQualityFormat
           
            self.requestId = manager.requestImageForAsset(asset, targetSize: CGSize(width: self.frame.size.width * UIScreen.mainScreen().scale, height: self.frame.size.height * UIScreen.mainScreen().scale), contentMode: PHImageContentMode.Default, options: option, resultHandler: {(result, info)->Void in
                self.imageView.image = result
            })
        }
    }

Thank you