AudioSessionInitialize(NULL, NULL, NULL, NULL);
UInt32 category = kAudioSessionCategory_PlayAndRecord;
AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(category), &category);
BOOL bSpeeker = YES;
UInt32 audioRouteOverride = bSpeeker ? kAudioSessionOverrideAudioRoute_Speaker :kAudioSessionOverrideAudioRoute_None;
AudioSessionSetProperty(kAudioSessionProperty_OverrideAudioRoute, sizeof (audioRouteOverride),&audioRouteOverride);
AudioSessionSetActive(true);
//kAudioSessionOverrideAudioRoute_Speaker ---表示扬声器
//kAudioSessionOverrideAudioRoute_None --- 默认值,听筒