Hey @danomatika
I don't have Genome app but I tested with some other MIDI supporting apps and I found out the crash happens depending on apps. I also tested this with your original ofxMIDI ExmpleIOS and I could get the same result.
Here's the list of apps that I tested below.
*No crashes: Xenon, Gadget, Nanostudio, Tabletop (I could remove port without errors when closing the app)
*Crashes: Music IO, Mobmuplat (crash happens when removing the port)
The interesting thing is that the crash didn't occur between two apps above (e.g Xenon and Music IO)
But it seems that some apps are causing my app to crash when removing MIDI port by closing the app.
Maybe some apps are using different Core MIDI protocols? I really don't know why this happens.
I can live with the bug for now since it's not the major issue but I would like to fix this at some point if possible.
Thank you very much and If you find a solution, please let us know.