在 Xamarin.iOS 中检查蓝牙状态（开/关）

Question

I am looking for a function that gets the status of the devices Bluetooth so I can tell the app users if it is on or off.

Current code keeps saying the Bluetooth is off even though it is on. Any help and guidance is appreciated!

public bool CheckBluetoothStatus()
        {
            bool status;

            if (state == CBCentralManagerState.PoweredOn)
            {
                status = true;
                bluetoothEnabledLbl.Text = "Bluetooth enabled";
                bluetoothEnabledAdviceLbl.Text = "Consider turning Bluetooth off if not in use or check to see if all connected devices are recognisable";

                return status;
            }
            else
            {
                status = false;
                bluetoothEnabledLbl.Text = "Bluetooth not enabled";

                return status;
            }
        }

Answer 1

Try this and if nothing changes it can be because of device version :

private CBCentralManagerState state; 
public bool CheckBluetoothStatus()
    {
        bool status;

        if (state == CBCentralManagerState.PoweredOn)
        {
            status = true;
            bluetoothEnabledLbl.Text = "Bluetooth enabled";
            bluetoothEnabledAdviceLbl.Text = "Consider turning Bluetooth off if not in use or check to see if all connected devices are recognisable";

        }
        else
        {
            status = false;
            bluetoothEnabledLbl.Text = "Bluetooth not enabled";

        }
            return status;
    }

Answer 2

There are two points need to pay attention when developing Xamarin iOS bluetooth application.

• First ,you need to run it in a physical device , can not testing bluetooth function in a simulator device . If that , you will always get follow console log with shared code :

2020-02-28 13:32:38.310442+0800 AppIOSBluetooth[36757:5394891] Bluetooth not enabled

• Second , you need to add permission for bluetooth application in info.plist file .When first running app , it will show permission popup window .

However , in info.plist , you can add the permission of Bluetooth easily as follow and will forget another most important permission :

<key>NSBluetoothPeripheralUsageDescription</key>
<string>Add BlueTooth Peripheral Permission</string>

That's not enough for Bluetooth . You also need to add another permission :

<key>NSBluetoothAlwaysUsageDescription</key>
<string>use Bluetooth</string>

In addition , there is an offical API doc about using Bluetooth in Xamarin iOS you can have a look .

public override void ViewDidLoad ()
{
    base.ViewDidLoad ();
    // Perform any additional setup after loading the view, typically from a nib.
    myDel = new MySimpleCBCentralManagerDelegate();
    var myMgr = new CBCentralManager(myDel, DispatchQueue.CurrentQueue);
}

public class MySimpleCBCentralManagerDelegate : CBCentralManagerDelegate
{
    override public void UpdatedState(CBCentralManager mgr)
    {
        if (mgr.State == CBCentralManagerState.PoweredOn)
        {
            Console.WriteLine("Bluetooth is available");
            //Passing in null scans for all peripherals. Peripherals can be targeted by using CBUIIDs
            CBUUID[] cbuuids = null;
            mgr.ScanForPeripherals(cbuuids); //Initiates async calls of DiscoveredPeripheral
                                                //Timeout after 30 seconds
            var timer = new Timer(30 * 1000);
            timer.Elapsed += (sender, e) => mgr.StopScan();
        }
        else
        {
            //Invalid state -- Bluetooth powered down, unavailable, etc.
            System.Console.WriteLine("Bluetooth is not available");
        }
    }
    public override void DiscoveredPeripheral(CBCentralManager central, CBPeripheral peripheral, NSDictionary advertisementData, NSNumber RSSI)
    {
        Console.WriteLine("Discovered {0}, data {1}, RSSI {2}", peripheral.Name, advertisementData, RSSI);
    }

}