Merge video is not working in iOS app - macos

Question

I have working on merge video functionality.
In my application I have one video with multiple tracks (total 10 tracks 9 video tracks and one audio track is common ).
Now I want to get 3 video from this multiple Tracks.
First video is combine with 1,4,7 track and
Second video is combine with 2,5,8 track and
Third video is combine with 3,6,9 track and
and Audio track is common for this three video.
I want to do this using following code.
AVPlayerItem* playerItem = [AVPlayerItem playerItemWithURL:[NSURL fileURLWithPath:urlSubItem.path]];
NSLog(#"%#",playerItem);
NSArray* arrTracks = [playerItem.asset tracksWithMediaType:AVMediaTypeVideo];
NSLog(#"%#",arrTracks);
NSArray* arrTracksText = [playerItem.asset tracksWithMediaType:AVMediaTypeText];
NSArray* arrTracksAudio = [playerItem.asset tracksWithMediaType:AVMediaTypeAudio];
NSLog(#"%#:%#",arrTracks,arrTracksAudio);
for (int i=0; i<3; i++) {
AVMutableComposition* mixComposition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionCommentaryTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionCommentaryTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, playerItem.asset.duration) ofTrack:[[playerItem.asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:kCMTimeZero error:nil];
CMTime currentTime = kCMTimeZero;
for (int k=0;k<[arrTracks count];k++) {
NSLog(#"%d",k%3);
if(k%3==i){
AVAssetTrack* trackCombineVideo = [arrTracks objectAtIndex:k];
AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
NSError* errors;
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(currentTime, trackCombineVideo.timeRange.duration) ofTrack:[arrTracks objectAtIndex:k] atTime:currentTime error:&errors];
if (errors) {
NSLog(#"wait error:%#",errors);
}
currentTime = trackCombineVideo.timeRange.duration;
}
}
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetPassthrough];
_assetExport.outputFileType = #"com.apple.quicktime-movie";
NSLog(#"file type %#",_assetExport.outputFileType);
_assetExport.outputURL = exportUrl // Document Directory Path;
_assetExport.shouldOptimizeForNetworkUse = YES;
Using this code 3 separate video is create but each video have a 3 different track.
Now, my question is how to create video with only one track ?

Answer 1

AVMutableCompositionTrack *compositionVideoTrack = [mixComposition
addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
for (int k=0;k<[arrTracks count];k++) {
NSLog(#"%d",k%3);
if(k%3==i){
AVAssetTrack* trackCombineVideo = [arrTracks objectAtIndex:k];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(currentTime, trackCombineVideo.timeRange.duration) ofTrack:[arrTracks objectAtIndex:k] atTime:currentTime error:&errors];
if (errors) {
NSLog(#"wait error:%#",errors);
}
currentTime = trackCombineVideo.timeRange.duration;
}
}
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPreset1280x720];
_assetExport.outputFileType = #"com.apple.quicktime-movie";
NSLog(#"file type %#",_assetExport.outputFileType);
_assetExport.outputURL = exportUrl // Document Directory Path;
_assetExport.shouldOptimizeForNetworkUse = YES;
_assetExport.timeRange = CMTimeRangeMake(kCMTimeZero, playerItem.asset.duration);