swift - 如何在 Swift 3 中每秒更改一次的视频中添加文本水印？

Question

我创建了一个显示当前时间的水印，但它不会每秒都在变化。我该怎么做才能使文本每秒更改一次？我想花时间制作安全录像之类的视频。下面的代码可以很好地在视频顶部添加文本。

  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

您需要添加一个计时器来更新 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)

}