我做了一个演示，通过视频URL从一堆图片中加载缩略图图像。现在我想在我的TableView列表中显示所有加载的缩略图图像，但问题是。如果我使用异步线程而不是TableView工作，TablView会挂起直到所有下载的缩略图图像。NE（滚动），但是所有的缩略图都会在20到25秒后加载。
这是我的密码
@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
}
}
请给我可能的解决方案，我想一些像sdwebimages，但它是有用的只有图像，而不是视频缩略图。我要斯威夫特3.0解决方案，提前谢谢
最佳答案
试试这个
do {
let asset = AVURLAsset(url: url , options: nil)
let imgGenerator = AVAssetImageGenerator(asset: asset)
imgGenerator.appliesPreferredTrackTransform = true
let cgImage = try imgGenerator.copyCGImage(at: CMTimeMake(0, 1), actualTime: nil)
thumbnail = UIImage(cgImage: cgImage)
} catch let error {
print("*** Error generating thumbnail: \(error.localizedDescription)")
}
}