How to Export Mp3 From Ipod-Library

Someday, our leader let me export videos, music and photos from Video, Music and Photos in iPad or iPhone. After looked up some articles, I found it was difficult to export mp3.

But, Nowadays, it came true to export mp3, so every format of ipod-library files can be exported.

Now, See how to do it.

• first, import some frameworks, such as MobileCoreServices.framework,MediaPlayer.framework,AVFoundation.framework

• second, query the media from ipod-library.

  //request videos and music come from system's Videos and Music 
  NSNumber *videoTypeNum = [NSNumber numberWithInteger:MPMediaTypeAny];
  
  MPMediaPropertyPredicate *videoPredicate = [MPMediaPropertyPredicate predicateWithValue:videoTypeNum forProperty:MPMediaItemPropertyMediaType];
  
  MPMediaQuery *videoQuery = [[MPMediaQuery alloc] init];
  [videoQuery addFilterPredicate: videoPredicate];
  _mediaItems = [[videoQuery items] copy];
  

*third, convert MPMediaItem to AVURLAsset, generate file name and file extension, then start export,the format of exported file is “MOV”.Finally, i need use NSFileManager rename the mov to mp3.

 MPMediaItem *mediaItem = [_mediaItems objectAtIndex:_count];

 //get the name of the file.
 NSString *songTitle = [mediaItem valueForProperty: MPMediaItemPropertyTitle];

 //convert MPMediaItem to AVURLAsset.
 AVURLAsset *sset = [AVURLAsset assetWithURL:[mediaItem valueForProperty:MPMediaItemPropertyAssetURL]];

//get the extension of the file.
NSString *fileType = [[[[sset.URL absoluteString] componentsSeparatedByString:@"?"] objectAtIndex:0] pathExtension];

//init export, here you must set "presentName" argument to "AVAssetExportPresetPassthrough". If not, you will can't export mp3 correct.
AVAssetExportSession *export = [[AVAssetExportSession alloc] initWithAsset:sset presetName:AVAssetExportPresetPassthrough];

NSLog(@"export.supportedFileTypes : %@",export.supportedFileTypes);
//export to mov format.
export.outputFileType = @"com.apple.quicktime-movie";

export.shouldOptimizeForNetworkUse = YES;

NSString *extension = ( NSString *)UTTypeCopyPreferredTagWithClass(( CFStringRef)export.outputFileType, kUTTagClassFilenameExtension);

NSLog(@"extension %@",extension);
NSString *path = [NSHomeDirectory() stringByAppendingFormat:@"/Documents/%@.%@",songTitle,extension];

NSURL *outputURL = [NSURL fileURLWithPath:path];
export.outputURL = outputURL;
[export exportAsynchronouslyWithCompletionHandler:^{

   if (export.status == AVAssetExportSessionStatusCompleted)
     {
        //then rename mov format to the original format.
         NSFileManager *manage = [NSFileManager defaultManager];

         NSString *mp3Path = [NSHomeDirectory() stringByAppendingFormat:@"/Documents/%@.%@",songTitle,fileType];

         NSError *error = nil;

         [manage moveItemAtPath:path toPath:mp3Path error:&error];

         NSLog(@"error %@",error);

      }
      else
      {
         NSLog(@"%@",export.error);
      }

}];

Some points you need notice:

• when you init AVAssetExportSession object, the “presetName” argument must be “AVAssetExportPresetPassthrough”.
• The “outputFileType” may be “com.apple.quicktime-movie”.

So easy, doesn’t it? Good night.