@kl3m3n That was quick! Yes, your code which restarts the advertising in the onDisconnect routine is much better. I believe I tried putting it there first but I don't think it would compile ("not in scope" error). Then I checked out that Kolban demo and just did it his way.
You must be a pretty good programmer to be handling all aspects of this by yourself. Even programmers that do both MCU programming and either smartphone or PC applications, are often not good writers- i.e. their documentation is poor. Your's is excellent.
FYI. I have used an IOS app called TechBasic which is something like GUI-O in that it lets you communicate with MCUs via Bluetooth. It is, however, a Basic interpreter running on the IOS device. So, its a bit more versatile but you do the actual programming/development on the IOS device itself. That's not ideal. The TechBasic app itself starts up like a PC IDE for Basic programming, and you can compose/edit or select & run your Basic programs from there.. So, it's not really a stand-alone app that a non-programmer can use easily. The auto-connect feature of GUI-O is quite superior in this respect.
Also, as far as I know, IOS only works in the BLE mode- not the legacy Bluetooth SPP mode. I happen to like that the Android OS lets you use legacy Bluettoth/SPP.
So, I agree- you are right to be hesitant about an IOS app. There would be a lot of adaptation you would likely have to do.
Again- thanks for your attention and efforts on my forum posts.😊
