//录音前设置
NSError *audioError = nil;
BOOL success = [[AVAudioSession sharedInstance] overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker error:&audioError];
if(!success)
{
NSLog(@"error doing outputaudioportoverride - %@", [audioError localizedDescription]);
}
//播放时
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *err = nil;
[audioSession setCategory :AVAudioSessionCategoryPlayback error:&err];