gistfile1.m

AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:[self.project.composition copy] presetName:AVAssetExportPresetPassthrough];
    NSURL* outputURL = [self createTempAssetFileURL:@"export"];
    exportSession.outputURL = outputURL;
    
//    exportSession.outputFileType=AVFileTypeQuickTimeMovie;
    exportSession.outputFileType=AVFileTypeMPEG4;
    
    [exportSession exportAsynchronouslyWithCompletionHandler:^{
        switch (exportSession.status) {
            case AVAssetExportSessionStatusFailed:{
                NSError *exportError = exportSession.error;
                
                NSLog (@"AVAssetExportSessionStatusFailed: %@", exportError);
                [self performSelectorOnMainThread:@selector (failedToSaveAsset:)
                                       withObject:nil
                                    waitUntilDone:NO];
                break;
            }
            case AVAssetExportSessionStatusCompleted: {
                NSLog (@"SUCCESS");
                [self performSelectorOnMainThread:@selector (uploadAsset:)
                                       withObject:outputURL
                                    waitUntilDone:NO];
                break;
            }
            default:
                NSLog(@"some other status : %d",exportSession.status);
                NSLog(@"%@",exportSession);
        };
    }];