ios - 删除 AVAudioSessionPortBuiltInMic 作为选项

Question

作为一个选项，我想删除 iPhone 的内置麦克风。虽然只有耳机出来的那个。基本上我想强制输出到耳机/蓝牙(如果可用)或主扬声器。 Apple 没有记录删除端口的方法。是否可以拦截路由更改，如果他们选择麦克风，则强制将其发送到扬声器？

Answer 1

是的，可以拦截路线更改。您需要观察 AVAudioSessionRouteChangeNotification 通知:

    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(audioRouteDidChanged:)
                                                 name:AVAudioSessionRouteChangeNotification
                                               object:nil];

然后你就可以区分路线变更类型了:

- (void)audioRouteDidChanged:(NSNotification *)notification
{
    // Here you can figure out the why audio route has been changed (if you need it)
    AVAudioSessionRouteChangeReason reason = [notification.userInfo valueForKey:AVAudioSessionRouteChangeReasonKey];
    switch (reason)
    {
        case AVAudioSessionRouteChangeReasonNewDeviceAvailable:
            NSLog(@"A user action (such as plugging in a headset) has made a preferred audio route available.");
            break;

        case AVAudioSessionRouteChangeReasonOldDeviceUnavailable:
            NSLog(@"The previous audio output path is no longer available.");
            break;

        default:
            NSLog(@"Other reasons. See documentation");
            break;
    }

    // And then make a decision to disable earpiece(aka receiver).
    // You can request current audio route description
    AVAudioSessionRouteDescription *routeDescription = [AVAudioSession sharedInstance].currentRoute;
    // then traverse through outputs and figure out if headset is present
    __block BOOL headsetExists = NO;
    [routeDescription.outputs enumerateObjectsUsingBlock:^(AVAudioSessionPortDescription *obj, NSUInteger idx, BOOL *stop) {
        if ([obj.portType isEqualToString:AVAudioSessionPortHeadphones])
        {
            headsetExists = YES;
            return ;
        }
    }];

    if (headsetExists == NO)
    {
        // force sound to speaker
        NSError *err = nil;
        [[AVAudioSession sharedInstance] overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker
                                                           error:&err];
    }
}