Low recording volume in combination with AVAudioSessionCategoryPlayAndRecord

Question

When I set:

[[AVAudioSession sharedInstance] setCategory:
    AVAudioSessionCategoryPlayAndRecord error:NULL];

…recording and playing works

Answer 1

For everyone with the same problem, redirect your output to the speaker:

[[AVAudioSession sharedInstance] setCategory:
    AVAudioSessionCategoryPlayAndRecord error:NULL];
UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
AudioSessionSetProperty(kAudioSessionProperty_OverrideAudioRoute,
    sizeof(audioRouteOverride), &audioRouteOverride);

That works.