Add watermark to recorded video and save - ios

Question

So I am trying to add a watermark to a previously recorded video using the following code, but when I view the video, there is no watermark. Can anyone help? I tried following the post at: iPhone Watermark on recorded Video.
public func addWatermarkToVideo(url: NSURL, completion:(url: NSURL?) -> Void) {
let videoAsset = AVURLAsset(URL: url)
let mixComposition = AVMutableComposition()
let compositionVideoTrack = mixComposition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid)
let clipVideoTrack: AVAssetTrack = videoAsset.tracksWithMediaType(AVMediaTypeVideo)[0]
do {
try compositionVideoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), ofTrack: clipVideoTrack, atTime: kCMTimeZero)
} catch {
print(error)
}
compositionVideoTrack.preferredTransform = videoAsset.tracksWithMediaType(AVMediaTypeVideo)[0].preferredTransform
//Add watermark
guard let myImage = UIImage(named: "Logo") else {
completion(url: nil)
return
}
let aLayer = CALayer()
aLayer.contents = myImage.CGImage
aLayer.frame = CGRectMake(5, 25, 100, 57)
aLayer.opacity = 0.65
let videoSize = videoAsset.tracksWithMediaType(AVMediaTypeVideo)[0].naturalSize
let parentLayer = CALayer()
let videoLayer = CALayer()
parentLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height)
videoLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height)
parentLayer.addSublayer(videoLayer)
parentLayer.addSublayer(aLayer)
let videoComp = AVMutableVideoComposition()
videoComp.renderSize = videoSize
videoComp.frameDuration = CMTimeMake(1,30)
videoComp.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, inLayer: parentLayer)
let instruction = AVMutableVideoCompositionInstruction()
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, mixComposition.duration)
let videoTrack = mixComposition.tracksWithMediaType(AVMediaTypeVideo)[0]
let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack)
instruction.layerInstructions = [layerInstruction]
videoComp.instructions = [instruction]
let paths = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)
let documentsDirectory: AnyObject = paths[0]
let dataPath = documentsDirectory.stringByAppendingPathComponent("VideoCache")
if (!NSFileManager.defaultManager().fileExistsAtPath(dataPath)) {
do {
try NSFileManager.defaultManager().createDirectoryAtPath(dataPath, withIntermediateDirectories: false, attributes: nil)
} catch {
print("Couldn't create path")
}
}
let tempURL = NSURL(fileURLWithPath: dataPath)
let completeMovieUrl = tempURL.URLByAppendingPathComponent("tether-\(NSDate()).mov")
if let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality) {
exporter.outputURL = completeMovieUrl
exporter.outputFileType = AVFileTypeMPEG4
exporter.exportAsynchronouslyWithCompletionHandler({ () -> Void in
switch exporter.status {
case .Failed:
print("failed \(exporter.error)")
completion(url: nil)
break
case .Cancelled:
print("cancelled \(exporter.error)")
completion(url: nil)
break
default:
print("complete")
completion(url: exporter.outputURL)
}
})
}
}

Answer 1

You've forgotten to add your videoComposition to the AVAssetExportSession:
exporter.outputFileType = AVFileTypeMPEG4 // You had this
exporter.videoComposition = videoComp // but had forgotten this
exporter.exportAsynchronouslyWithCompletionHandler({ // ...