iOS issue checking if Bluetooth is ON

Question

I need to check if Bluetooth is On.

I use this code:

func startDetectingBluetoothState() {
        if self.centralManager == nil {
            self.centralManager = CBCentralManager(delegate: self, queue: self.workingQueue, options: [CBCentralManagerOptionShowPowerAlertKey: false])
        }
    }

func centralManagerDidUpdateState(_ central: CBCentralManager) {
        let state = central.state
        DispatchQueue.main.async { [weak self] in
            // notify observers about state change
            self?.stateObservers.invokeDelegates { stateObserver in
                stateObserver.bluetoothStateChanged()
            }
        }
    }

I start the app on iPhone X 11.3 (Bluetooth is On in the Settings), then almost immidiatly it enters in centralManagerDidUpdateState(_ central: CBCentralManager) with state == .poweredOff. So the value is wrong. Then I turn off Bluetooth in Settings, centralManagerDidUpdateState(_ central: CBCentralManager) function is not called (because the previous state it detected was .poweredOff), then I turn on Bluetooth and centralManagerDidUpdateState(_ central: CBCentralManager) is called with .poweredOn value. Then it detects every state change properly. But if I restart the app and Bluetooth is On, it can't detect it again. If during start the Bluetooth is Off, everything is OK.

I have another device iPhone 6+ 11.2.5, where everything works as a charm :)

score 3 · Answer 1 · answered Apr 13 '18 at 11:43

3

You need to implement CBCentralManagerDelegate. Below is the sample code which might help you to check the condition -

 var centralManager:CBCentralManager!

 in init() or viewDidLoad()
 {
     centralManager = CBCentralManager()
     centralManager.delegate = self
 }

func centralManagerDidUpdateState(_ central: CBCentralManager) {

  if central.state == .poweredOn {
     print("Bluetooth is connected")
  }
  else if central.state == .poweredOff{
     print("Bluetooth is not Connected.")
  }
}

answered Apr 13 '18 at 11:43

Abhishek

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What's the difference with code? As I said: in delegate it only returns .poweredOff state – Paul T. Apr 13 '18 at 11:53
Have you tried my code. Also have you tried switching on bluetooth once it is off to get the state? – Abhishek Apr 13 '18 at 11:54
Yes, I tried your code, it doesn't work with my iPhone X, but it works with my iPhone 6+, but my code works on 6+ too – Paul T. Apr 18 '18 at 09:12
Can you please confirm your ios versions on iPhone 6+ and iPhoneX – Abhishek Apr 18 '18 at 09:17
iPhone X is 11.3, iPhone 6+ is 11.2.5 – Paul T. Apr 18 '18 at 09:19
I think the issue might be with ios 11.3. Would suggest you to try following steps and see if it might help you https://www.howtoisolve.com/ios-11-bluetooth-not-working/ – Abhishek Apr 18 '18 at 09:19
I can upvote ) but it's almost the same code as mine ) – Paul T. Apr 18 '18 at 09:29

score 0 · Answer 2 · answered Apr 13 '18 at 12:38

Use this Code Working for you

 var centralManager:CBCentralManager!

 override func viewDidLoad()
{
    super.viewDidLoad()

    // This will trigger centralManagerDidUpdateState
    centralManager = CBCentralManager(delegate: self, queue: nil)

}

 func centralManagerDidUpdateState(_ central: CBCentralManager)
{
    print("Central Manager did update state")

    if (central.state == .poweredOn)
    {

        self.centralManager?.scanForPeripherals(withServices: nil, options: [CBCentralManagerScanOptionAllowDuplicatesKey: false])
    }
    else 
     {
        // Bluetooth is unavailable for some reason

        // Give feedback
        var message = String()
        switch central.state
        {
        case .unsupported:
            message = "Bluetooth is unsupported"
        case .unknown:
            message = "Bluetooth state is unkown"
        case .unauthorized:
            message = "Bluetooth is unauthorized"
        case .poweredOff:
            message = "Bluetooth is powered off"
        default:
            break
        }
        print(message)

        UIAlertView(
            title: "Bluetooth unavailable",
            message: message,
            delegate: nil,
            cancelButtonTitle: "OK")
            .show()
    }
}

no, this code returns .powerOff as well for my iPhone X – Paul T. Apr 18 '18 at 09:13 — Paul T., Apr 18 '18 at 09:13

iOS issue checking if Bluetooth is ON

2 Answers2