This looks quite useful, and is a universal app too so should come in handy in all environments. I haven’t checked to see if it’s ad supported or with IAPs, so if you check it out please let me know.
Here’s what app description:
MIDI Scope allows you to monitor MIDI activity using your iOS device. Features include the ability to filter events by individual type or by group as well as MIDI Channel. A comprehensive interpretation of each event packet is displayed. Raw packet data is shown in both decimal and hexadecimal formats. Please send feature requests and trouble reports to the support email listed on our web site.