I'm using Matt Gallagher's awesome AudioStreamer example to play an audio file via AudioSession. All works, except that on my iPhone 4 I get audio playback out of my bottom speaker, and not the ear speaker. I inserted the following code to no avail.
UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_None;
AudioSessionSetProperty (
kAudioSessionProperty_OverrideAudioRoute,
sizeof (audioRouteOverride),
&audioRouteOverride
);