VideoEdit Watermark

   if let asset = firstAsset {
            // 2 - Create AVMutableComposition object. This object will hold your AVMutableCompositionTrack instances.
            let cmp = AVMutableComposition()
            
            // 3 - Video track
            let track = cmp.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
            guard let sourceVideoTrack = asset.tracks(withMediaType: AVMediaTypeVideo).first else {return}
            
            try! track.insertTimeRange(CMTimeRangeMake(kCMTimeZero, asset.duration), of: sourceVideoTrack, at: kCMTimeZero)

            
            // 3.1 - Create AVMutableVideoCompositionInstruction
            let instruction = AVMutableVideoCompositionInstruction()
            instruction.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration)

            
            // 3.2 - Create an AVMutableVideoCompositionLayerInstruction for the video track and fix the orientation.
            let videolayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
            let videoAssetTrack =  asset.tracks(withMediaType: AVMediaTypeVideo).first
            
            var videoAssetOrientation: UIImageOrientation
            var isVideoAssetPortrait = false
            let videoTransform = videoAssetTrack!.preferredTransform
            if (videoTransform.a == 0 && videoTransform.b == 1.0 && videoTransform.c == -1.0 && videoTransform.d == 0) {
                videoAssetOrientation = .right
                isVideoAssetPortrait = true
            }
            if (videoTransform.a == 0 && videoTransform.b == -1.0 && videoTransform.c == 1.0 && videoTransform.d == 0) {
                videoAssetOrientation = .left
                isVideoAssetPortrait = true
            }
            if (videoTransform.a == 1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == 1.0) {
                videoAssetOrientation =  .up
            }
            if (videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0) {
                videoAssetOrientation = .down
            }
            
            videolayerInstruction.setTransform((videoAssetTrack!.preferredTransform), at: kCMTimeZero)
            videolayerInstruction.setOpacity(0.0, at: asset.duration)
 
            // 3.3 - Add instructions
            instruction.layerInstructions = [videolayerInstruction]
            
            let animComp = AVMutableVideoComposition()

            var  naturalSize: CGSize
            if isVideoAssetPortrait {
                naturalSize = CGSize(width: track.naturalSize.height, height: track.naturalSize.width)
            } else {
                naturalSize = track.naturalSize
            }
            
            animComp.renderSize = naturalSize
            animComp.instructions = [instruction]
            animComp.frameDuration = CMTimeMake(1, 30);
            
            let parentLayer = CALayer()
            let videoLayer = CALayer()
            let aLayer = CALayer()
            aLayer.frame = CGRect(x: 100, y: 100, width: 100, height: 100)
            aLayer.bounds = CGRect(x: 0, y: 0, width: 100, height: 100)
            aLayer.contents = UIImage(named: "mask.png")?.cgImage
            
            aLayer.opacity = 0.5
            aLayer.backgroundColor = UIColor.red.cgColor

            parentLayer.frame = CGRect(x: 0, y: 0, width: naturalSize.width, height: naturalSize.height)
            videoLayer.frame = CGRect(x: 0, y: 0, width: naturalSize.width, height: naturalSize.height)
            
            parentLayer.backgroundColor = UIColor.blue.cgColor
            videoLayer.backgroundColor = UIColor.green.cgColor
            
            parentLayer.addSublayer(videoLayer)
            parentLayer.addSublayer(aLayer)
            animComp.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, in: parentLayer)

            // 4 - Get path
            let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
            let dateFormatter = DateFormatter()
            dateFormatter.dateStyle = .long
            dateFormatter.timeStyle = .short
            let date = dateFormatter.string(from: Date())
            let savePath = (documentDirectory as NSString).appendingPathComponent("mergeVideo-\(date).mov")
            let url = URL(fileURLWithPath: savePath)

            // 5 - Create Exporter
            guard let exporter = AVAssetExportSession(asset: cmp, presetName: AVAssetExportPresetHighestQuality) else { return }
            exporter.outputURL = url
            exporter.outputFileType = AVFileTypeQuickTimeMovie
            exporter.shouldOptimizeForNetworkUse = true
            exporter.videoComposition = animComp
            
            // 6 - Perform the Export
            exporter.exportAsynchronously() {
                DispatchQueue.main.async { _ in
                    self.exportDidFinish(exporter)
                }
            }
        }