For a video camera app I want the user to be able to adjust the input gain on the audio.
On iOS8 an iPhone 6 and 5, I used to be able to do this through:
float desiredGain = ...;
NSError *error;
[[AVAudioSession sharedInstance] setInputGain:desiredGain error:&error];
However on an iPhone 6s / iOS9 I am no longer able to do this. AVAudioSession's isInputGainSettable returns NO for this setup.
I am not sure if this is a hardware or an OS issue / change.
Is there a way to adjust the input gain in iPhone 6s / iOS9?
No input gain control on 6s. Using isInputGainSettable will let you know if the input ports allow for the ability to set the input gain or not. Check, then do the appropriate thing for each case if you care to. Different hardware will always equal different capabilities over the lifetime of your application.