Resonate starts empty by design. Use Add a folder and pick any folder from Files, iCloud Drive or another app. Everything inside it, including subfolders, is copied into Resonate and indexed. You can also drag files straight into the Resonate folder in Finder or the Files app — they are picked up on next launch.
Files are copied rather than referenced, so playback keeps working even if the original moves or is deleted.
Only recognised audio is imported: MP3, M4A, AAC, FLAC, WAV, AIFF, ALAC and CAF. Use Settings ▸ Rescan for new files after adding anything outside the app.
Discover matches against a catalogue built from your own library, so it needs music imported first. Building runs automatically after an import; you can check progress and rebuild it under Settings ▸ Discover catalogue. Naming songs you don't own additionally requires an internet connection.
Separated stems are stored uncompressed and are roughly ten times the size of the original file. Resonate keeps up to 2 GB and clears the least recently used first. Clear them all under Settings ▸ Delete all separated stems.
Settings ▸ Restore purchases, signed in with the same Apple Account used to buy. The lifetime unlock is a one-time purchase and never expires.
It needs a device with a Taptic Engine — iPhone 7 and later. It does not work on iPad or in the Simulator. Check it is enabled and turned up under Settings ▸ Playback.