mixer.swift

//: Playground - noun: a place where people can play
import UIKit
import AVFoundation

do {
    let documentDirectoryURL = try! NSFileManager.defaultManager().URLForDirectory(.DocumentDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: true)
    let outputURL = documentDirectoryURL.URLByAppendingPathComponent("output.mov")
    
    if (NSFileManager.defaultManager().fileExistsAtPath(outputURL.path!)) {
        try NSFileManager.defaultManager().removeItemAtPath(outputURL.path!)
    }
    
    let audioPath = NSBundle.mainBundle().pathForResource("audio", ofType: "wav")
    let audioURL:NSURL = NSURL.fileURLWithPath(audioPath!)
    let audio = AVURLAsset.init(URL: audioURL)
    let audioAssetTrack = audio.tracksWithMediaType(AVMediaTypeAudio).first!

    let videoPath = NSBundle.mainBundle().pathForResource("video", ofType: "mp4")
    let videoURL:NSURL = NSURL.fileURLWithPath(videoPath!)
    let video = AVURLAsset.init(URL: videoURL)
    let videoAssetTrack = video.tracksWithMediaType(AVMediaTypeVideo).first!
    
    let imagePath = NSBundle.mainBundle().pathForResource("photo", ofType: "jpg")
    let imageURL:NSURL = NSURL.fileURLWithPath(imagePath!)

    let composition = AVMutableComposition.init()
    let compositionAudioTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: kCMPersistentTrackID_Invalid)
    let compositionVideoTrack = composition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid)

    try compositionAudioTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, audioAssetTrack.timeRange.duration), ofTrack: audioAssetTrack, atTime: kCMTimeZero)
    
    try compositionVideoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, audioAssetTrack.timeRange.duration), ofTrack: videoAssetTrack, atTime: kCMTimeZero)
    
    //let cgImage = UIImage.init(data: NSData.init(contentsOfURL: imageURL)!)!.CGImage
    //let videoAssetTrack =
    
    //try compositionVideoTrack.in
    
    //let videoWriter = try AVAssetWriter.init(URL: outputURL, fileType: AVFileTypeMPEG4)
    
    let exporter = AVAssetExportSession.init(asset: composition, presetName: AVAssetExportPresetHighestQuality)
    exporter?.outputURL = outputURL
    exporter?.outputFileType = AVFileTypeQuickTimeMovie
    exporter?.shouldOptimizeForNetworkUse = true
    
    let group = dispatch_group_create()
    dispatch_group_enter(group)
    exporter?.exportAsynchronouslyWithCompletionHandler {
        dispatch_group_leave(group)
    }
    
    while exporter?.status == .Waiting || exporter?.status == .Exporting {
        print("Progress: \((exporter?.progress)! * 100.0)%.")
        dispatch_group_wait(group, dispatch_time(DISPATCH_TIME_NOW, Int64(500 * NSEC_PER_MSEC)))
    }
    
} catch {
    print("Something went wrong")
}

/**
Oct 26 23:54:01  Merger[5938] <Error>: CGContextSaveGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
Oct 26 23:54:01  Merger[5938] <Error>: CGContextTranslateCTM: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
Oct 26 23:54:01  Merger[5938] <Error>: CGContextRestoreGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
2015-10-26 23:54:01.517 Merger[5938:191866] 23:54:01.516 WARNING:  40: ERROR: couldn't get default input device, ID = 0, err = 0!
2015-10-26 23:54:01.523 Merger[5938:191866] 23:54:01.523 WARNING:  803: The default input device 0x0 '(null)' has no input channels.
Progress: 0.0%.
*/