I've searched relentlessly for a solution but to no avail. The issues is that I bought some expensive Bose Quiet 35 Bluetooth headphones to use with my iPhone 4. The iPhone is an older model and I only use it as a MP3 player. The problem is that occasionally the music stops and I have to swipe up on the home screen, where Airplay is selected and the bluetooth headphone is not selected. I have to re-select the headphone for bluetooth playback to resume. After 5 minutes the music stops and and I have to go back and re-select headphone. This completely destroys the listening experience. What is odd that if I reboot the phone sometimes it helps and airplay doesn't interrupt anymore. But after a while the issue returns. Rebooting doesn't always work.
Also, when airplay interrupts and I do nothing after a few seconds playback on bluetooth resumes. Very irritating. This is an issue with the iPhone because the same happens with my car bluetooth too.
At first I thought maybe other Mac devices (iMacs and MacBooks) were trying to connect or a passing car with an Apple device triggered the airplay interruption.
It is a completely frustrating mystery. I even tried wiping the iPhone and resetting. The problem disappeared for a while but then returned.
I've also searched everywhere to see if there was a way to totally kill the airplay option on the iPhone but haven't found one.
I even tried to jailbreak the iPhone in hope that maybe a Cydia app could do this. But due to this particular model I wasn't able to get the jailbreaking software to work.