我做了一个演示,可以从视频URL上一堆加载缩略图.现在我想在tableview列表中显示所有加载的缩略图,但是问题是.如果我使用异步的话,tablview会挂起直到下载完所有缩略图线程比我的tableview工作正常(滚动),但是所有缩略图在20到25秒后加载.

这是我的代码

@IBOutlet weak var tableviewList:UITableView!

var listArray:[String] = ["https://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4",

"http://techslides.com/demos/sample-videos/small.mp4",

"http://jplayer.org/video/m4v/Big_Buck_Bunny_Trailer.m4v",

"https://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4",

"http://techslides.com/demos/sample-videos/small.mp4",

"http://jplayer.org/video/m4v/Big_Buck_Bunny_Trailer.m4v",

"https://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4",

"http://techslides.com/demos/sample-videos/small.mp4",

"http://jplayer.org/video/m4v/Big_Buck_Bunny_Trailer.m4v"

]

override func viewDidLoad() {

super.viewDidLoad()

self.tableviewList.register(UINib(nibName: "ListTableViewCell", bundle: nil), forCellReuseIdentifier: "ListTableViewCell")

for aryString in self.listArray

{

self.createThumbnailOfVideoFromFileURL(aryString)

}

}

override func didReceiveMemoryWarning() {

super.didReceiveMemoryWarning()

// Dispose of any resources that can be recreated.

}

public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int

{

return self.listArray.count

}

public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell

{

let cell = tableView.dequeueReusableCell(withIdentifier: "ListTableViewCell", for: indexPath) as! ListTableViewCell

let strUrl = self.listArray[indexPath.row]

DispatchQueue.global(qos: .userInitiated).async {

// Download file or perform expensive task

cell.imageviewThumb?.image = self.getThumbnailFrom(path: URL.init(string:strUrl )!)

DispatchQueue.main.async {

// Update the UI

}

}

cell.selectionStyle = UITableViewCellSelectionStyle.none

return cell

}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

let stringUrl:String = self.listArray[indexPath.row]

let videoUrl = NSURL(string:stringUrl)

let player = AVPlayer(url:videoUrl as! URL)

let playerviewController = AVPlayerViewController()

playerviewController.player = player

self.present(playerviewController, animated: true, completion: {

playerviewController.player?.play()

})

}

public func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat

{

return 300

}

func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {

return true

}

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {

if (editingStyle == UITableViewCellEditingStyle.delete) {

// handle delete (by removing the data from your array and updating the tableview)

}

}

func getThumbnailFrom(path: URL) -> UIImage? {

do {

let asset = AVURLAsset(url: path , options: nil)

let imgGenerator = AVAssetImageGenerator(asset: asset)

imgGenerator.appliesPreferredTrackTransform = true

let cgImage = try imgGenerator.copyCGImage(at: CMTimeMake(0, 1), actualTime: nil)

let thumbnail = UIImage(cgImage: cgImage)

return thumbnail

} catch let error {

print("*** Error generating thumbnail: \(error.localizedDescription)")

return nil

}

}

请给我可能需要的解决方案,例如SDWebImages,但它仅对图像有用而不对视频缩略图有用.我想要快速的3.0解决方案.在此先感谢