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?