Hello,
I’d just like to mention that I had this same issue. The iOS app would not detect my pi B+ despite it being on the same subnet and pingable. My phone was connected to the same WiFi network as my pi. I had also changed the default password on my pi so maybe that’s the cause?
Regardless, I was able to install via SSH and now it appears to be working.
Maybe it would be helpful to have the iOS app recommend the SSH installation method if it’s not able to detect the device after a certain period of time.
Thanks,
Ian