gistfile1.m

- (void)_processAudio:(AVURLAsset *)audioAsset
              present:(NSString *)preset
              handler:(void(^)(double percentComplete, NSError* error))handler
{
    NSString* tempDir = NSTemporaryDirectory();
    NSString* exportPath = [tempDir stringByAppendingPathComponent:[NSString randomString]];
    
    if ([[NSFileManager defaultManager] fileExistsAtPath:exportPath])
    {
        [[NSFileManager defaultManager] removeItemAtPath:exportPath
                                                   error:nil];
    }
    
    NSURL* exportURL = [NSURL fileURLWithPath:exportPath];
    
    AVAssetExportSession* exportSession = [[AVAssetExportSession alloc] initWithAsset:audioAsset presetName:preset];
    
    exportSession.outputURL = exportURL;
    exportSession.shouldOptimizeForNetworkUse = YES;
    exportSession.outputFileType = AVFileTypeAppleM4V;
    
    __weak PLGYouTubeUploader* wself = self;
    
    NSTimer* progressTimer = [NSTimer scheduledTimerWithTimeInterval:0.1
                                                               block:^{
                                                                   
                                                                   switch (exportSession.status)
                                                                   {
                                                                       case AVAssetExportSessionStatusFailed:
                                                                           [wself _failAudioProcessing:handler];
                                                                           break;
                                                                       case AVAssetExportSessionStatusCancelled:
                                                                           [wself _failAudioProcessing:handler];
                                                                           break;
                                                                       default:
                                                                           handler(exportSession.progress, nil);
                                                                           break;
                                                                   }
                                                                   
                                                               }
                                                             repeats:YES];
    
    [exportSession exportAsynchronouslyWithCompletionHandler:^{
        
        [progressTimer invalidate];
        
        if (exportSession.status == AVAssetExportSessionStatusCompleted)
        {
            NSString* path = exportSession.outputURL.path;
        }
        else
        {
            SHOW_ALERT_ERROR(@"")
        }
        
    }];
    
}