How to merge video and audio files?

Question

My question is: How to merge video and audio files that has almost the same duration?

I searched and got some answers to this question. However when I try the code t

Answer 1

(Answered by the OP by an edit in the question. Converted to a community wiki answer. See Question with no answers, but issue solved in the comments (or extended in chat) )

The OP wrote:

I solved my problem.

For the ones who have same problem as I did, here is the simple solution:

a.Delete the following code:

CMTime start=CMTimeMake(0, 600);
CMTime duration=CMTimeMake(600, 600);
CMTimeRange range=CMTimeRangeMake(start, duration);
exporter.timeRange=range;

b.(optional)Rewrite completion handler:

[exporter exportAsynchronouslyWithCompletionHandler:^{ 
    switch ([exporter status]) {
        case AVAssetExportSessionStatusFailed:
            NSLog(@"Export failed: %@", [[exporter error] localizedDescription]);
            break;
        case AVAssetExportSessionStatusCancelled:
            NSLog(@"Export canceled");
            break;
        default:
            break;
    } 
}];

c.Then wait long enough for the program to complete writing.