Convert data to .caf audio in ios

Currently I'm calling webservice and get the datas from the webservices. I'm trying to make the audio file but it doesn't create any playable audio file. I can create it .caf file format but the audio is not playing.

NSString *dataPath = [[[Global sharedGlobals] documentsDirectoryPath] stringByAppendingPathComponent:[NSString stringWithFormat:@"/%@/recent.caf",_incidentID]];
[data writeToFile:dataPath atomically:YES];