Preparing Custom Alert Sounds
Local and remote notifications can specify custom alert sounds to be played when the notification is delivered. You can package the audio data in an aiff, wav, or caf file. Because they are played by the system-sound facility, custom sounds must be in one of the following audio data formats:
- Linear PCM
- MA4 (IMA/ADPCM)
- µLaw
- aLaw
Place custom sound files in your app bundle or in the Library/Sounds folder of your app’s container directory. Custom sounds must be under 30 seconds when played. If a custom sound is over that limit, the default system sound is played instead.
You can use the afconvert tool to convert sounds. For example, to convert the 16-bit linear PCM system sound Submarine.aiff to IMA4 audio in a CAF file, use the following command in the Terminal app:
afconvert /System/Library/Sounds/Submarine.aiff ~/Desktop/sub.caf -d ima4 -f caff -v
For information on how to associate a sound file with a notification, see Adding a Sound to the Notification Content.
