iOS AVMutableComposition Add text overlay - swift

Question

can someone please advise.
I am trying to add a text overlay (title) to a video I am composing using AVFoundation. I found a few online resources (see http://stackoverflow.com/questions/21684549/add-a-text-overlay-with-avmutablevideocomposition-to-a-specific-timerange)
However all these resources are in Objective-C.
My project is in Swift and I cannot find any related resources in Swift.
I am not able to get the text to overlay properly is seems distorted as if the frame in which is gets rendered is skewed...
See picture Distorted text in AVPlayer
I have attempted to convert the Objective-C code I found to Swift but obviously I am missing something.
Below is the code I am using.
(I used some code for the player and the video file from:www.raywenderlich.com/90488/calayer-in-ios-with-swift-10-examples
func MergeUnWeldedVideoByUserPref(showInBounds: CGRect) -> (AVMutableComposition, AVMutableVideoComposition)
{
let fps: Int32 = 30
// 1 - Create AVMutableComposition object. This object will hold your AVMutableCompositionTrack instances.
let mixComposition = AVMutableComposition()
// 2 - Create a video track for each of the video assests. Add your media data to the appropriate tracks
//let url = NSBundle.mainBundle().URLForResource("colorfulStreak", withExtension: "m4v")!
let url = NSBundle.mainBundle().URLForResource("colorfulStreak", withExtension: "m4v")!
let avAsset = AVAsset(URL: url)
let track = mixComposition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
let segmentInMovie = CMTimeRangeMake(kCMTimeZero, avAsset.duration)
let videoTrack = avAsset.tracksWithMediaType(AVMediaTypeVideo)[0]
do
{
try track.insertTimeRange(segmentInMovie, ofTrack: videoTrack, atTime: kCMTimeZero)
} catch{
print("Failed to load track")
}
let mainInstruction = AVMutableVideoCompositionInstruction()
mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, avAsset.duration)
let instruction = videoCompositionInstructionForTrack(showInBounds, track: track, asset: avAsset)
mainInstruction.layerInstructions.append(instruction)
let mainComposition = AVMutableVideoComposition()
mainComposition.instructions = [mainInstruction]
mainComposition.frameDuration = CMTimeMake(1, fps)
mainComposition.renderSize = CGSize(width: showInBounds.width, height: showInBounds.height)
let textLayer = CATextLayer()
textLayer.backgroundColor = UIColor.clearColor().CGColor
textLayer.foregroundColor = UIColor.whiteColor().CGColor
textLayer.string = "T E S T"
textLayer.font = UIFont(name: "Arial", size: 18)
textLayer.shadowOpacity = 0.5
textLayer.alignmentMode = kCAAlignmentCenter
textLayer.frame = CGRectMake(5, 5, 100, 50)
textLayer.shouldRasterize = true
textLayer.rasterizationScale = showInBounds.width / videoTrack.naturalSize.width
let parentLayer = CALayer()
let videoLayer = CALayer()
parentLayer.frame = CGRectMake(0, 0, showInBounds.width, showInBounds.height);
videoLayer.frame = CGRectMake(0, 0, showInBounds.width, showInBounds.height);
parentLayer.addSublayer(videoLayer)
parentLayer.addSublayer(textLayer)
mainComposition.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, inLayer: parentLayer)
return (mixComposition, mainComposition)
}

Answer 1

There is nothing wrong with your Swift interpretation and is rather an issue with the rendering engine of the simulator. I tried your code on the simulator and it indeed looked skewed and distorted but when compiling to the device it worked beautifully.