使用iPhone SDK同时播放和录制声音吗？

Question

I'm trying to detect input from the mic and also play sounds, which can be toggled on or off, but are always playing when the mic listener is active.

I've initialized my AVAudioSession in the viewDidLoad method like so:

AVAudioSession *session = [AVAudioSession sharedInstance];
NSError *err = nil;
[session setCategory:AVAudioSessionCategoryPlayAndRecord error:&err];
[session setActive:YES error:&err];

Then setup the sound that's supposed to be played:

NSURL *activeUrl = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/audio_file.caf", [[NSBundle mainBundle] resourcePath]]];
activePlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:activeUrl error:nil];
activePlayer.numberOfLoops = -1;
activePlayer.currentTime = 0;
activePlayer.volume = -1.5;

And I'm using the SCListener class to do the recording. When I run this on the phone, the recorder works just fine, but the sound won't loop even when I call play for it in the viewDidLoad method.

Any ideas?

Answer 1

Thanks so much for the responses. I did actually figure this out a while back, but never got around to updating this. Turned out to be very simple. You have to set category of AVAudioSession to AVAudioSessionCategoryPlayAndRecord.

Pretty much all the documentation you need is here in the class reference:

http://developer.apple.com/library/ios/#documentation/AVFoundation/Reference/AVAudioSession_ClassReference/Reference/Reference.html

Answer 2

I had a similar issue to you - the code worked on the simulator, but not on the device. I had this problem using Cocos2D (Denshion) along with AVAudioRecorder & AVAudioPlayer.

The main issue seems to be that AVAudioRecorder and AVAudioPlayer set the AVAudioSessionCategory on your behalf, but if you manipulate it yourself, they seem to remember that you're "self managing" it and stop managing it for you.

See this blog post that helped me (although I still haven't solved the issue myself; I'll update this post when I do solve it).