如何將文字水印添加到Swift 3中每秒更改的視頻中？

Question

我已經創建了一個顯示當前時間的水印，但它不會每秒都改變一次。我如何做到這一點，所以文字每秒都在變化？我想在安全錄像等視頻上留出時間。以下代碼可以很好地在視頻頂部添加文本。

func waterMark(){ 
     let filePath: String = Bundle.main.path(forResource: "Zombie", ofType: "mp4")! 
     let videoAsset = AVURLAsset(url: URL(fileURLWithPath: filePath), options: nil) 
     let mixComposition = AVMutableComposition() 
     let compositionVideoTrack: AVMutableCompositionTrack? = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid) 

     let clipVideoTrack = videoAsset.tracks(withMediaType: AVMediaTypeVideo)[0] 
     try? compositionVideoTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: clipVideoTrack, at: kCMTimeZero) 
     compositionVideoTrack?.preferredTransform = videoAsset.tracks(withMediaType: AVMediaTypeVideo)[0].preferredTransform 
     let videoSize: CGSize = clipVideoTrack.naturalSize 
     let aLayer = CALayer() 
     aLayer.contents = (Any).self 

     aLayer.frame = CGRect(x: videoSize.width - 65, y: videoSize.height - 75, width: 57, height: 57) 
     aLayer.opacity = 0.65 
     let parentLayer = CALayer() 
     let videoLayer = CALayer() 
     parentLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height) 
     videoLayer.frame = CGRect(x: 0, y: 0, width: videoSize.width, height: videoSize.height) 
     parentLayer.addSublayer(videoLayer) 
     parentLayer.addSublayer(aLayer) 
     let titleLayer = CATextLayer() 



     let dateFormatter = DateFormatter() 
    dateFormatter.timeStyle = .medium 

    // titleLayer.backgroundColor = UIColor.black.cgColor 
    titleLayer.string = String((dateFormatter.string(from: Date() as Date))) 

     titleLayer.font = UIFont.systemFont(ofSize: 100) 
     titleLayer.shadowOpacity = 0.5 
     titleLayer.frame = parentLayer.frame 
     titleLayer.display() 
     //You may need to adjust this for proper display 
     parentLayer.addSublayer(titleLayer as? CALayer ?? CALayer()) 
     let videoComp = AVMutableVideoComposition() 
     videoComp.renderSize = videoSize 
     videoComp.frameDuration = CMTimeMake(1, 30) 
     videoComp.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, in: parentLayer) 
     let instruction = AVMutableVideoCompositionInstruction() 
     instruction.timeRange = CMTimeRangeMake(kCMTimeZero, mixComposition.duration) 
     let videoTrack = mixComposition.tracks(withMediaType: AVMediaTypeVideo)[0] 
     let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack) 
     instruction.layerInstructions = [layerInstruction] 
     videoComp.instructions = [instruction] 
     let assetExport = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality) 
     //AVAssetExportPresetPassthrough 
     assetExport?.videoComposition = videoComp 
     var paths: [Any] = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true) 

     let documentsDirectory: String = paths[0] as? String ?? "" 
     let VideoName: String = "\(documentsDirectory)/mynewwatermarkedvideo.mp4" 

     let exportUrl = URL(fileURLWithPath: VideoName) 
     if FileManager.default.fileExists(atPath: VideoName) { 
      print(VideoName) 
      try? FileManager.default.removeItem(atPath: VideoName) 
      print("file found again") 
     } 
     assetExport?.outputFileType = AVFileTypeQuickTimeMovie 
     assetExport?.outputURL = exportUrl 
     assetExport?.shouldOptimizeForNetworkUse = true 
     //[strRecordedFilename setString: exportPath]; 
     assetExport?.exportAsynchronously(completionHandler: {() -> Void in 
      DispatchQueue.main.async(execute: {() -> Void in 
      }) 
     }) 
     print("Completed") 

    } 



///call 
waterMark() 

Answer 1

您需要添加一個計時器來更新titleLayer。

var timer: NSTimer? 

override func viewDidLoad() { 
    super.viewDidLoad() 

    timer = Timer.scheduledTimer(timeInterval: 60, target: self, selector: #selector(self.getTimeOfDate), userInfo: nil, repeats: true) 
} 

func getTimeOfDate() { 
    var curDate = Date() 

    timeLabel.text = formatter.string(from: curDate) 

}