iOS11蓝牙有些奇怪

Question

When I switch off the Bluetooth in setting, then I use CBCentralManager to get the state of the Bluetooth like this:

self.bluetoothManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];

the system will display a alert like this: system alert

The current state of Bluetooth is CBManagerStatePoweredOff . But when I switch off the Bluetooth in control center, this alert is not show anymore even if the current state of Bluetooth is still CBManagerStatePoweredOff .

How could I remind the user to switch on the Bluetooth in this situation?

Answer 1

You can remind the users by implementing the following delegate method.

//Bluetooth state delegation
#pragma mark - CBCentralManagerDelegate

- (void)centralManagerDidUpdateState:(CBCentralManager *)central
{
    NSString *stateString = nil;
    switch(self.CBManager.state)
    {
        case CBManagerStateResetting:
        stateString = @"The connection with the system service was momentarily lost, update imminent.";
        break;
        case CBManagerStateUnsupported:
        stateString = @"The platform doesn't support Bluetooth Low Energy."; break;
        case CBManagerStateUnauthorized: stateString = @"The app is not authorized to use Bluetooth Low Energy.";
        break;
        case CBManagerStatePoweredOff:
        stateString = @"Bluetooth is currently powered off.";
        break;
        case CBManagerStatePoweredOn:
        [self.beaconManager startMonitoringForRegion:self.museumsRegion];
        [self.beaconManager startRangingBeaconsInRegion: self.museumsRegion];
        break;
        case CBManagerStateUnknown:
        stateString = @"State unknown, update imminent.";
        break;
    }
    NSLog(@"%@", stateString);
}

Now the user should be informed automatically.

Answer 2

You can disable system BlueTooth alert by using CBCentralManagerOptionShowPowerAlertKey in options dict.

NSDictionary *options = @{CBCentralManagerOptionShowPowerAlertKey: @NO};
self.bluetoothManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil options:options];

Then you can using deleget method centralManagerDidUpdateState: to popup you custom alert.