Rotate video 90 degrees in Swift 4 - swift

Question

I've been trying to search for this all day, but all answers point to older versions of Swift or Obj-C.
I tried layer instructions, but AVMutableComposition has no member instructions. I remember this being really easy with just an affineTransform, but now I no longer know where I found this.
var mainVideoURL:URL!
let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
let tempPath = paths[0] + "/mainVideo.mp4"
if(FileManager.default.fileExists(atPath: tempPath)){
guard (try? FileManager.default.removeItem(atPath: tempPath)) != nil else {
print("remove path failed")
self.enableButtons(enabled:true)
return
}
}
mainVideoURL = URL(fileURLWithPath: tempPath)
let firstAsset = AVURLAsset(url: fileURL)
let mixComposition = AVMutableComposition()
// repeat video number of times
let videoRepeat = photoVideoRepeats
for i in 0 ... videoRepeat - 1 {
do {
try mixComposition.insertTimeRange(CMTimeRangeMake(kCMTimeZero, firstAsset.duration),
of: firstAsset,
at: kCMTimeZero + CMTimeMultiply(firstAsset.duration,Int32(i)))
} catch _ {
print("Failed to load first track")
}
}
guard let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality) else { return }

Answer 1

After my video was recorded, I was able to do a CGAffineTransform on a AVMutableCompositionTrack.
In my case I needed to merge an audio track with the video, but you can see where the transforms take place:
func mergeVideoAndAudio(videoUrl: URL,
audioUrl: URL) -> AVAsset {
let mixComposition = AVMutableComposition()
var mutableCompositionVideoTrack = [AVMutableCompositionTrack]()
var mutableCompositionAudioTrack = [AVMutableCompositionTrack]()
var mutableCompositionAudioOfVideoTrack = [AVMutableCompositionTrack]()
//start merge
let aVideoAsset = AVAsset(url: videoUrl)
let aAudioAsset = AVAsset(url: audioUrl)
let compositionAddVideo = mixComposition.addMutableTrack(withMediaType: .video,
preferredTrackID: kCMPersistentTrackID_Invalid)
let compositionAddAudio = mixComposition.addMutableTrack(withMediaType: .audio,
preferredTrackID: kCMPersistentTrackID_Invalid)
let compositionAddAudioOfVideo = mixComposition.addMutableTrack(withMediaType: .audio,
preferredTrackID: kCMPersistentTrackID_Invalid)
let aVideoAssetTrack: AVAssetTrack = aVideoAsset.tracks(withMediaType: AVMediaType.video)[0]
let aAudioOfVideoAssetTrack: AVAssetTrack? = aVideoAsset.tracks(withMediaType: AVMediaType.audio).first
let aAudioAssetTrack: AVAssetTrack = aAudioAsset.tracks(withMediaType: AVMediaType.audio)[0]
// Default must have tranformation
compositionAddVideo?.preferredTransform = aVideoAssetTrack.preferredTransform
var transforms = aVideoAssetTrack.preferredTransform
if UIDevice.current.orientation == UIDeviceOrientation.landscapeLeft {
transforms = transforms.concatenating(CGAffineTransform(rotationAngle: CGFloat(-90.0 * .pi / 180)))
transforms = transforms.concatenating(CGAffineTransform(translationX: 1280, y: 0))
}
else if UIDevice.current.orientation == UIDeviceOrientation.landscapeRight {
transforms = transforms.concatenating(CGAffineTransform(rotationAngle: CGFloat(90.0 * .pi / 180)))
transforms = transforms.concatenating(CGAffineTransform(translationX: 1280, y: 0))
}
else if UIDevice.current.orientation == UIDeviceOrientation.portraitUpsideDown {
transforms = transforms.concatenating(CGAffineTransform(rotationAngle: CGFloat(180.0 * .pi / 180)))
transforms = transforms.concatenating(CGAffineTransform(translationX: 0, y: 720))
}
compositionAddVideo?.preferredTransform = transforms
mutableCompositionVideoTrack.append(compositionAddVideo!)
mutableCompositionAudioTrack.append(compositionAddAudio!)
mutableCompositionAudioOfVideoTrack.append(compositionAddAudioOfVideo!)
do {
try mutableCompositionVideoTrack[0].insertTimeRange(CMTimeRangeMake(start: CMTime.zero,
duration: aVideoAssetTrack.timeRange.duration),
of: aVideoAssetTrack,
at: CMTime.zero)
//In my case my audio file is longer then video file so i took videoAsset duration
//instead of audioAsset duration
try mutableCompositionAudioTrack[0].insertTimeRange(CMTimeRangeMake(start: CMTime.zero,
duration: aVideoAssetTrack.timeRange.duration),
of: aAudioAssetTrack,
at: CMTime.zero)
// adding audio (of the video if exists) asset to the final composition
if let aAudioOfVideoAssetTrack = aAudioOfVideoAssetTrack {
try mutableCompositionAudioOfVideoTrack[0].insertTimeRange(CMTimeRangeMake(start: CMTime.zero,
duration: aVideoAssetTrack.timeRange.duration),
of: aAudioOfVideoAssetTrack,
at: CMTime.zero)
}
} catch {
print(error.localizedDescription)
}
return mixComposition
}