Generate images from AVAsset with AVAssetImageGenerator and from AVPlayerItem with AVPlayerItemVideoOutput

AVThumbnailGen.swift

    /// Generate thumbnail with AVAssetImageGenerator
    func generateThumbnailFromAsset(asset: AVAsset, forTime time: CMTime) -> UIImage {
        let imageGenerator = AVAssetImageGenerator(asset: asset)
        imageGenerator.appliesPreferredTrackTransform = true
        var actualTime: CMTime = kCMTimeZero
        do {
            let imageRef = try imageGenerator.copyCGImageAtTime(time, actualTime: &actualTime)
            let image = UIImage(CGImage: imageRef)
            return image
        } catch let error as NSError {
            print("\(error.description). Time: \(actualTime)")
        }
    }
    
    /// Generate thumbnail with pixel buffer
    func generateThumbnailFromPlayerItem(item: AVPlayerItem) -> UIImage {
        let videoOutput = AVPlayerItemVideoOutput(pixelBufferAttributes: [kCVPixelBufferPixelFormatTypeKey as String : NSNumber(unsignedInt: kCVPixelFormatType_32BGRA)])
        item.addOutput(videoOutput)
        if let pixelBuffer = videoOutput.copyPixelBufferForItemTime(item.currentTime(), itemTimeForDisplay: nil) {
            let ciImage = CIImage(CVPixelBuffer: pixelBuffer)
            let tempContext = CIContext(options: nil)
            let videoImage = tempContext.createCGImage(ciImage, fromRect: CGRect(x: 0, y: 0, width: CVPixelBufferGetWidth(pixelBuffer), height: CVPixelBufferGetHeight(pixelBuffer)))
            let image = UIImage(CGImage: videoImage)
            return image
        }
        return nil
    }