Connect Bluetooth devices to Apple Watch

func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String: Any], rssi RSSI: NSNumber ) {

    // Add to an array of discovered peripherals,
    // then connect to the peripheral.

    central.connect(peripheral, options: nil)

}

func handle(_ backgroundTasks: Set<WKRefreshBackgroundTask>) {
    for task in backgroundTasks {
        if let refreshTask = task as? WKApplicationRefreshBackgroundTask {
            // Insert your code to start background work here.
            central.connect(peripheral, options: nil)
            refreshTask.expirationHandler = {
                // Insert your code to cancel existing work here.
                if let peripheral = self.bluetoothReceiver.connectedPeripheral {
                    self.central.cancelPeripheralConnection(peripheral)
                }
                refreshTask.setTaskCompletedWithSnapshot(false)
            }
        }
    }
}

// If the app gets woken up to handle a background refresh task, this method will be called
// if a peripheral was disconnected when the app had previously transitioned to the
// background.
func centralManager(_ central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: Error?) {
    connectedPeripheral = nil
    delegate?.didCompleteDisconnection(from: peripheral)
}

// In your WatchKit Extension delegate:

func didCompleteDisconnection(from peripheral: CBPeripheral) {
    if let refreshTask = currentRefreshTask {
        task.setTaskCompletedWithSnapshot(false)
        currentRefreshTask = nil
    }
}