Swift-水平滚动收集视图单元（自动和手动）

Question

In my app I have used AVPlayer to play video. By using the following function I am getting frames from the video in each second (if video length is 2 minutes(120 seconds) I am getting 120 frames). This frames are stored in an array videoFrames

var videoFrames = [UIImage]()
 func generateFrames(url: NSURL, fromTime: Float64) {
        let asset: AVAsset = AVAsset(url: url as URL)
        let assetImgGenerate: AVAssetImageGenerator = AVAssetImageGenerator(asset: asset)
        assetImgGenerate.maximumSize = CGSize(width: 300, height: 300)
        assetImgGenerate.appliesPreferredTrackTransform = true
        let time: CMTime = CMTimeMakeWithSeconds(fromTime, 600)
        var img: CGImage?
        do {
            img = try assetImgGenerate.copyCGImage(at: time, actualTime: nil)
        } catch {
        }
        if img != nil {
            let frameImg: UIImage = UIImage(cgImage: img!)
            videoFrames.append(frameImg)
        } else {
//            return nil
        }
    }

This video frames are placed in a horizontal scrolling UICollectionView like this

Now I need to move the UICollectionView cells automatically from right to left and also allow the user(if wishes) to scroll manually. (Exactly the same functionality when you play video in iPhone/iPod etc)

I found this code...

func autoScroll () {
    let co = collectionView.contentOffset.x
    let no = co + 1

    UIView.animate(withDuration: 0.01, delay: 0, options: .curveEaseInOut, animations: { [weak self]() -> Void in
        self?.collectionView.contentOffset = CGPoint(x: no, y: 0)
    }) { [weak self](finished) -> Void in
        self?.autoScroll()
    }
}

but before finishing video the auto scroll finishes. I can't determine what should be the value of withDuration: parameter in UIView.animate() . Also if I add this autoScroll () function I can't scroll the UICollectionView cells manually. But I need both automatically & manually. Any assistance would be appreciated.

Answer 1

What you can do is initially create a variable called index with value 0. Now create a Timer function that will fire every 1 second and repeat itself, inside the selector for the Timer just use scrollToItem method of the collection view and keep incrementing the index variable.

Now when the user begins scrolling in the collectionView just invalidate the timer and calculate the index based on the scroll amount. After the scrolling, restart the timer again. Remember to move the video to the appropriate location as well!

Edit:

var timer : Timer!

var index = 0

override func viewDidAppear(_ animated:Bool){

     //call super here

     timer = Timer(timeInterval: 1, target: self, selector: #selector(handleTimer), userInfo: nil, repeats: true)
}

func handleTimer(){

    index += 1

    let indexPath = IndexPath(row: index, section: 0)

    main.collectionView.scrollToItem(at: indexPath, at: .left, animated: true)
}