iOS录音功能真机调试失败

AVAudioSession * session = [AVAudioSession sharedInstance];
_session = session;
NSError * sessionError;
[session setCategory:AVAudioSessionCategoryPlayAndRecord error:&sessionError];
if(session == nil)
NSLog(@"Error creating session: %@", [sessionError description]);
else
[session setActive:YES error:nil];