Question

[audioSession setCategory:AVAudioSessionCategoryPlayAndRecord fooError: &fooError];
//Activate the session
[audioSession setActive:YES fooError: &fooError];

The warning i receive is

warning: ‘AVAudioSession’ may not respond to ‘-setActive:fooError:’

Answer 1

The warning already tells you what the problem is: The AVAudioSession methods are called -setCategory:error: and -setActive:error:, not -setCategory:fooError: and -setActive:fooError:, respectively. You can change parameter names any way you want but not method names:

[audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error: &fooError];
//Activate the session
[audioSession setActive:YES error: &fooError];