如何检测蓝牙耳机是否已插入 IOS 8？

Question

In my project, I use AVAudioSession to detect any headphone is plugged or unplugged. But in this case, I can't detect when bluetooth device is plugged. Here is my code for headphone state.

 - (void)audioRouteChangeListenerCallback:(NSNotification*)notification
    {

    NSDictionary *interuptionDict = notification.userInfo;

    NSInteger routeChangeReason = [[interuptionDict valueForKey:AVAudioSessionRouteChangeReasonKey] integerValue];

    switch (routeChangeReason) {

        case AVAudioSessionRouteChangeReasonNewDeviceAvailable:
            //NSLog(@"AVAudioSessionRouteChangeReasonNewDeviceAvailable");

            NSLog(@"Headphone/Line plugged in");

            [_soundButtonOutlet setImage:[UIImage imageNamed:@"sound-on.png"] forState:UIControlStateNormal];

            _headSetState=YES;

            break;

        case AVAudioSessionRouteChangeReasonOldDeviceUnavailable:
            NSLog(@"AVAudioSessionRouteChangeReasonOldDeviceUnavailable");

            NSLog(@"Headphone/Line was pulled. Stopping player....");

             [_soundButtonOutlet setImage:[UIImage imageNamed:@"sound-off.png"] forState:UIControlStateNormal];
            if(_isPlaying==YES)
            {


            [self.player pause];

            [_audioButtonOutlet setImage:[UIImage imageNamed:@"play.png"] forState:UIControlStateNormal];

            _isPlaying=NO;

            }
            _headSetState=NO;

            break;

        case AVAudioSessionRouteChangeReasonCategoryChange:
            // called at start - also when other audio wants to play
            NSLog(@"AVAudioSessionRouteChangeReasonCategoryChange");


            break;
    }



- (BOOL)isHeadsetPluggedIn

{

    AVAudioSessionRouteDescription* route = [[AVAudioSession sharedInstance] currentRoute];
    for (AVAudioSessionPortDescription* desc in [route outputs]) {

        if ([[desc portType] isEqualToString:AVAudioSessionPortHeadphones])
        {
        [_soundButtonOutlet setImage:[UIImage imageNamed:@"sound-on.png"] forState:UIControlStateNormal];
            _headSetState=YES;
            return YES;
        }
        else
        {
    [_soundButtonOutlet setImage:[UIImage imageNamed:@"sound-off.png"] forState:UIControlStateNormal];
            _headSetState=NO;
            return NO;

        }
    }


    return NO;
}

}


- viewWillAppear  {

 [AVAudioSession sharedInstance];

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

[self isHeadsetPluggedIn];

}

So how can I detect if a bluetooth headset plugged or not iOS 8?

Answer 1

You can detect currently active bluetooth output devices (instead of input devices)

Swift Code:

import AVFoundation
func bluetoothAudioConnected() -> Bool{
  let outputs = AVAudioSession.sharedInstance().currentRoute.outputs
  for output in outputs{
    if output.portType == AVAudioSessionPortBluetoothA2DP || output.portType == AVAudioSessionPortBluetoothHFP || output.portType == AVAudioSessionPortBluetoothLE{
      return true
    }
  }
  return false
}

Bluetooth devices are based on the following question: What's the difference among AVAudioSessionPortBluetoothHFP, A2DP and LE?

I hope it helps someone

---

Edit for Swift 5.1 (Thanks iago849 for the fix)

var bluetoothDeviceConnected: Bool {
    !AVAudioSession.sharedInstance().currentRoute.outputs.compactMap {
        ($0.portType == .bluetoothA2DP ||
        $0.portType == .bluetoothHFP ||
        $0.portType == .bluetoothLE) ? true : nil
    }.isEmpty
}

Answer 2

I was able to detect whether a bluetooth headset (HFP) device was currently connected using the following:

NSArray *arrayInputs = [[AVAudioSession sharedInstance] availableInputs];
for (AVAudioSessionPortDescription *port in arrayInputs)
{
    if ([port.portType isEqualToString:AVAudioSessionPortBluetoothHFP])
    {
        bHas = YES;
        break;
    }
}

However, your AVAudioSession category must be set as AVAudioSessionCategoryPlayAndRecord in order for this to work. If it isn't, the port will not show up in the list even if the HFP device is connected.

Answer 3

You can detect it with routeChangeNotification :

    func activateHeadPhonesStatus(){
        NotificationCenter.default.addObserver(self, selector: #selector(audioRouteChangeListener(_:)), name: AVAudioSession.routeChangeNotification, object: nil)
    }
    
    @objc func audioRouteChangeListener(_ notification:Notification) {
        guard let userInfo = notification.userInfo,
              let reasonValue = userInfo[AVAudioSessionRouteChangeReasonKey] as? UInt,
              let reason = AVAudioSession.RouteChangeReason(rawValue:reasonValue) else {
            return
        }
        if reason == .newDeviceAvailable {
            let session = AVAudioSession.sharedInstance()
            for output in session.currentRoute.outputs where output.portType == AVAudioSession.Port.bluetoothA2DP {
                print("Bluetooth Headphone Connected")
                break
            }
        }
    }