How to reliably detect if an external keyboard is connected on iOS 9?

Question

Previous to iOS 9, the most reliable method of determining whether an external keyboard is connected was to listen for UIKeyboardWillShowNotification and make a

Answer 1

You could try checking for peripherals that are advertising services using Core Bluetooth

CBCentralManager *centralManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil]; 
[centralManager scanForPeripheralsWithServices:nil options:nil];

And you should implement the delegate:

- (void)centralManager:(CBCentralManager * _Nonnull)central
 didDiscoverPeripheral:(CBPeripheral * _Nonnull)peripheral
     advertisementData:(NSDictionary * _Nonnull)advertisementData
                  RSSI:(NSNumber * _Nonnull)RSSI{

}