我正在向用戶顯示影像選擇器以從圖庫中選擇視頻。那行得通，我傳遞了媒體型別 ["public.movi??e"] 并顯示了畫廊的所有視頻以供選擇。當用戶選擇它時，我會在我的委托中收到：
extension VNInventoryCollectionVC: UIImagePickerControllerDelegate {
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey: Any]) {
let info = convertFromUIImagePickerControllerInfoKeyDictionary(info)
if let pickedImage = info[convertFromUIImagePickerControllerInfoKey(UIImagePickerController.InfoKey.originalImage)] as? UIImage
{
pickImageCallback?(pickedImage)
}
if let videoURL = info["UIImagePickerControllerReferenceURL"] as? URL
{
print(videoURL)
pickImageCallback?(videoURL)
}
dismiss(animated: true)
}
}
回呼后，我嘗試從該視頻創建影像縮略圖，而這正是我無法做到的：
let thumbnail = getThumbnailFrom(path: multimedia.video!)
cell.image.image = thumbnail
生成縮略圖的函式是：
func getThumbnailFrom(path: URL) -> UIImage? {
do {
print("Video URL: \(path)")
print("Video absolute URL: \(path.absoluteURL)")
//let asset = AVURLAsset(url: path.absoluteURL! , options: nil)
var asset : AVAsset = AVAsset(url: path.absoluteURL) as! AVAsset
let imgGenerator = AVAssetImageGenerator(asset: asset)
imgGenerator.appliesPreferredTrackTransform = true
let cgImage = try imgGenerator.copyCGImage(at: CMTimeMake(value: 0, timescale: 1), actualTime: nil)
let thumbnail = UIImage(cgImage: cgImage)
return thumbnail
} catch let error {
print("*** Error generating thumbnail: \(error.localizedDescription)")
return nil
}
}
在控制臺中顯示的視頻網址是：
Video URL: assets-library://asset/asset.MP4?id=84D1CEDD-7AE4-4FE5-897E-47608DC2CFF0&ext=MP4
Video absolute URL: assets-library://asset/asset.MP4?id=84D1CEDD-7AE4-4FE5-897E-47608DC2CFF0&ext=MP4
顯示的錯誤是無法打開檔案。斷線是：
let cgImage = try imgGenerator.copyCGImage(at: CMTimeMake(value: 0, timescale: 1), actualTime: nil)
我想問題出在 url 上，我有一個資產 url，我需要一個絕對檔案路徑或類似的東西。
uj5u.com熱心網友回復：
使用UIImagePickerController.InfoKey.mediaURL鑰匙進入的資訊字典。UIImagePickerController.InfoKey.referenceURL已棄用。
func didSelectVideo(at url: URL) {
let asset = AVAsset(url: url)
let generator = AVAssetImageGenerator(asset: asset)
generator.appliesPreferredTrackTransform = true
let cgImage = try! generator.copyCGImage(at: CMTimeMake(value: 0, timescale: 1), actualTime: nil)
let thumbnail = UIImage(cgImage: cgImage)
cell.image.image = thumbnail
}
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
dismiss(animated: true) {
guard let url = info[.mediaURL] as? URL else { return }
self.didSelectVideo(at: url)
}
}
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