ChordMaps2 is a "MIDI controller." It doesn't create any sound on its own. It works by sending note information to a second app, a synthesizer app running in the background. Here are the setup steps.

1 – Open a synth app, choose a sound, and play a couple notes to make sure it's working. (If you don't have a synth app, look in the App Store for the free app "Synth One." This will get you started.)

2 – Important: Look in the synth app's "Settings" for "Background Audio" and make sure it is "On."

(Also, the synth app should be responding on Midi Channel 1. For most synth apps, this is already set up when you open the app.)

3 – Open ChordMaps2 and touch "Info." (the circled "i" at the top left or right)

4 – When the Info pane opens, set the "Midi Channel" numbers to 1211345167.

5 – Also look under "Midi Destinations" for the name of the synth app. Touch the name. A blue checkmark will appear. This establishes the midi connection.

6 – Touch "Done" at the top. This returns you to the ChordMaps2 playing screen where you can begin playing.

Note regarding GarageBand – Some synth apps, GarageBand being one of them, do not "advertise" their presence, and so their names do not appear in the list of Midi Destinations. In this situation a "midi bridge" app is required.

I use the free app called FreEWI as a midi bridge.

1 – Search for "Audeonic Apps" in the App Store. Then look for FreEWI and install it.

2 – Open FreEWI, and leave it running in the background.

3 – Open GarageBand and select a sound. Play a couple notes to make sure it's working. Also turn on "Run in Background" under Settings / Advanced.

3 – Open ChordMaps2 and touch "Info" (the circled "i" at the top left or right). Look for FreEWI in the list of Midi Destinations. Touch the name FreEWI. A blue checkmark will appear.

4 – Touch "Done" at the top, and start playing. (GarageBand will respond to the midi information being sent to FreEWI.)