StackOverflow2013

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POSaving ID3 tags on iOS
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copied!<p>So I want to make my app edit and save ID3 tags. I found on some site a long time ago on how to read them, here is this code in my app:</p> <pre><code>-(NSDictionary*)MP3InfoDictionary { AudioFileID fileID = nil; OSStatus err = noErr; err = AudioFileOpenURL( (CFURLRef) self, kAudioFileReadPermission, 0, &fileID); if (err != noErr) { //NSLog(@"AudioFileOpenURL failed"); } UInt32 id3DataSize = 0; char * rawID3Tag = NULL; err = AudioFileGetPropertyInfo(fileID, kAudioFilePropertyID3Tag, &id3DataSize, NULL); if (err != noErr) { NSLog(@"AudioFileGetPropeetyInfo failed for ID3 tag"); } //NSLog(@"id3 data size is %lu bytes",id3DataSize); rawID3Tag = (char *) malloc(id3DataSize); if (rawID3Tag == NULL) { //NSLog(@"could not allocated %lu bytes of memory for ID3 tag", id3DataSize); } err = AudioFileGetProperty(fileID, kAudioFilePropertyID3Tag, &id3DataSize, rawID3Tag); if (err != noErr) { NSLog(@"AudioFileGetProperty failed for ID3 tag"); } //NSLog(@"read %lu bytes of ID3 info", id3DataSize); CFDictionaryRef piDict = nil; UInt32 piDataSize = sizeof(piDict); free(rawID3Tag); err = AudioFileGetProperty(fileID, kAudioFilePropertyInfoDictionary, &piDataSize, &piDict); if (err != noErr) { //NSLog(@"AudioFileGetProperty failed for property info dictionary"); } //NSLog(@"Property info:%@", (NSDictionary*)piDict); //CFShow(piDict); NSDictionary *MP3InfoDictionary = (NSDictionary*)piDict; if (MP3InfoDictionary != NULL) { return MP3InfoDictionary; } return nil; } </code></pre> <p>This code is in a NSURL category, the url is a file url of a mp3 in the documents directory of the iOS. It works 100%, I get all the titles, artwork, lyrics, etc. But now I want to save and overwrite values of the mp3 like artist, title, etc. On another post on here a guy posted that you use AudioFileSetProperty(), how do I use it correctly?</p> <p>Apparently it's because of the kAudioFileReadPermission but It tells me that the mp3 is only readable, but that can't be true because another app I have can change ID3 tags and can on the same mp3 I've tried to edit.</p>

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