Turning Your iPad into a Midi Controller for GarageBand on Mac

What you need is a Midi controller app for iPad. For example, the following app costs 170 yen.

AirMidi https://itunes.apple.com/jp/app/airmidi/id646384689?mt=8

No need for Midi cables or connection interfaces.

For connection methods, I referred to another app's instructions here. Connect through WiFi to your MAC | Beatsurfing http://beatsurfing.net/connect-mac-wifi/

This app costs 1000 yen on the AppStore. It seems to be capable of creating a Midi controller.

In the example on this page, it creates an ad-hoc network, but you can also connect similarly via an access point. The method is also described in the help section within the AirMidi app (text only).

When I tried using it, I found the latency to be quite high, making it difficult to use for live performances. However, it seems perfectly fine for simple recording tasks in GarageBand.