Progress bar for AVAssetExportSession

Question

I\'ve got an app that exports an AVMutableComposition into a .mov file, and I\'d like for the user to see the status of the export with a progress bar

Answer 1

Use below lines of code.

AVAssetExportSession *session = [AVAssetExportSession exportSessionWithAsset:composition presetName:AVAssetExportPresetMediumQuality];
self.exportSession = session;

// 出力先（テンポラリファイル）の設定。
NSString *filePath = NSTemporaryDirectory();
filePath = [filePath stringByAppendingPathComponent:@"out.mov"];
[[NSFileManager defaultManager] removeItemAtPath:filePath error:nil];
session.outputURL = [NSURL fileURLWithPath:filePath];

// 出力タイプの設定。
session.outputFileType = AVFileTypeQuickTimeMovie;

// 非同期エクスポートの開始。
[session exportAsynchronouslyWithCompletionHandler:^{
    if (session.status == AVAssetExportSessionStatusCompleted) {
        // フォトアルバムへの書き込み。
        ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
        [library writeVideoAtPathToSavedPhotosAlbum:session.outputURL completionBlock:^(NSURL *assetURL, NSError *error){
            if (error) {
                self.resultLabel.text = [NSString stringWithFormat:@"アセット書き込み失敗\n%@", error];
            } else {
                self.resultLabel.text = [NSString stringWithFormat:@"完了\n%@", assetURL];
            }
        }];
        [library autorelease];
    } else if (session.status == AVAssetExportSessionStatusCancelled) {
        self.resultLabel.text = @"エクスポート中断";
    } else {
        self.resultLabel.text = [NSString stringWithFormat:@"エクスポート失敗\n%@", session.error];
    }
}];


dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
    while (session.status == AVAssetExportSessionStatusExporting) {
        dispatch_sync(dispatch_get_main_queue(), ^{
            self.progressView.progress = session.progress;
        });
    }
});

Reference Link : https://github.com/keijiro/iOS4BookSampleCode/blob/master/3.3.SimpleExport/Classes/SimpleExportViewController.m

Answer 2

Same issue i have faced in iOS 8.0, i resolved it using dispatch quee

- (void)convertVideoToLowQuailtyWithInputURL:(NSURL*)inputURL outputURL:(NSURL*)outputURL handler:(void (^)(AVAssetExportSession*))handler{

[[NSFileManager defaultManager] removeItemAtURL:outputURL error:nil];
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:inputURL options:nil];

exportSession2 = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetLowQuality];
exportSession2.outputURL = outputURL;
exportSession2.outputFileType = AVFileTypeQuickTimeMovie;

[exportSession2 exportAsynchronouslyWithCompletionHandler:^(void)
 {
     handler(exportSession2);
 }];

 dispatch_async(dispatch_get_main_queue(), ^(void){

      self.exportProgressBarTimer = [NSTimer scheduledTimerWithTimeInterval:.1 target:self selector:@selector(updateExportDisplay) userInfo:nil repeats:YES];
 });

}

Answer 3

Swift 3 example

Using Notification Center to send progress updates to listeners

//`AVAssetExportSession` code above
var exportProgressBarTimer = Timer() // initialize timer
if #available(iOS 10.0, *) {
    exportProgressBarTimer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { timer in
    // Get Progress
    let progress = Float((exportSession?.progress)!);
    if (progress < 0.99) {
       let dict:[String: Float] = ["progress": progress]
       NotificationCenter.default.post(name: Notification.Name("ProgressBarPercentage"), object: nil, userInfo: dict)
    }
  }
}

// on exportSession completed
exportSession?.exportAsynchronously(completionHandler: {
   exportProgressBarTimer.invalidate(); // remove/invalidate timer
   if exportSession?.status == AVAssetExportSessionStatus.completed { 
      // [....Some Completion Code Here]
   }
})

Then setup the notification center listener anywhere you'd like using

NotificationCenter.default.addObserver(self, selector: #selector(self.statusUpdate(_:)), name: NSNotification.Name(rawValue: "ProgressBarPercentage"), object: nil)

Answer 4

I came up with an answer a while back so I'll post it in case it can help someone:

First, in the method in which you call AVAssetExportSession you've got to set up a timer to update your UIProgressView once you've initiated the export:

//`AVAssetExportSession` code here
    self.exportProgressBarTimer = [NSTimer scheduledTimerWithTimeInterval:.1 target:self selector:@selector(updateExportDisplay) userInfo:nil repeats:YES];
...

Then you need a method to update your display taking into account that the progress property on AVAssetExportSession goes from 0 - 1:

- (void)updateExportDisplay {
    self.exportProgressBar.progress = exportSession.progress;
    if (self.exportProgressBar.progress > .99) {
        [self.exportProgressBarTimer invalidate];
    }
}