从连接到AVPlayer的CALayer获取UIImage(从视频播放中提取帧)

import AVFoundation

func extractFrameFromVideo(url: URL, time: CMTime) -> UIImage? {
    let asset = AVURLAsset(url: url)
    let playerItem = AVPlayerItem(asset: asset)
    let player = AVPlayer(playerItem: playerItem)
    
    let playerLayer = AVPlayerLayer(player: player)
    playerLayer.frame = CGRect(x: 0, y: 0, width: 320, height: 240) // 设置视频显示区域
    
    let imageGenerator = AVAssetImageGenerator(asset: asset)
    imageGenerator.appliesPreferredTrackTransform = true
    
    var thumbnailImage: UIImage?
    
    let semaphore = DispatchSemaphore(value: 0)
    
    imageGenerator.generateCGImagesAsynchronously(forTimes: [NSValue(time: time)]) { requestedTime, image, actualTime, result, error in
        if let image = image {
            thumbnailImage = UIImage(cgImage: image)
        }
        semaphore.signal()
    }
    
    player.play()
    semaphore.wait()
    player.pause()
    
    return thumbnailImage
}

let videoURL = URL(fileURLWithPath: "path/to/video.mp4")
let time = CMTimeMakeWithSeconds(5, preferredTimescale: 600)
let thumbnail = extractFrameFromVideo(url: videoURL, time: time)