BLE notifications.

ble.swift

import CoreBluetooth
import UIKit

class ViewController: UIViewController, CBCentralManagerDelegate, CBPeripheralDelegate {
    
    var manager:CBCentralManager!
    var peripheral:CBPeripheral!
    
    let BEAN_NAME = "Bean+"
    let BEAN_SCRATCH_UUID = CBUUID(string: "a495ff21-c5b1-4b44-b512-1370f02d74de")
    let BEAN_SERVICE_UUID = CBUUID(string: "a495ff20-c5b1-4b44-b512-1370f02d74de")
    
    override func viewDidLoad() {
        super.viewDidLoad()
        manager = CBCentralManager(delegate: self, queue: nil)
    }
    
    func centralManagerDidUpdateState(_ central:CBCentralManager) {
        if central.state == CBManagerState.poweredOn {
            central.scanForPeripherals(withServices: nil, options: nil)
            debugPrint("Searching ...")
        } else {
            debugPrint("Bluetooth not available.")
        }
    }
    
    func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
        let device = (advertisementData as NSDictionary).object(forKey: CBAdvertisementDataLocalNameKey) as? NSString
        
        if device?.contains(BEAN_NAME) == true {
            debugPrint("Found Bean.")
            
            self.manager.stopScan()
            self.peripheral = peripheral
            self.peripheral.delegate = self
            
            manager.connect(peripheral, options: nil)
        }
    }
    
    func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
        debugPrint("Getting services ...")
        peripheral.discoverServices(nil)
    }
    
    func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
        for service in peripheral.services! {
            let thisService = service as CBService
            
            debugPrint("Service: ", service.uuid)
            
            if service.uuid == BEAN_SERVICE_UUID {
                debugPrint("Using scratch.")
                peripheral.discoverCharacteristics(nil, for: thisService)
            }
        }
    }
    
    func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
        debugPrint("Enabling ...")
        
        for characteristic in service.characteristics! {
            let thisCharacteristic = characteristic as CBCharacteristic
            
            debugPrint("Characteristic: ", thisCharacteristic.uuid)
            
            if thisCharacteristic.uuid == BEAN_SCRATCH_UUID {
                debugPrint("Set to notify: ", thisCharacteristic.uuid)
                
                // Prepare to show data
                
                self.peripheral.setNotifyValue(true, for: thisCharacteristic)
            }
        }
    }
    
    func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
        if characteristic.uuid == BEAN_SCRATCH_UUID {
            let content = String(data: characteristic.value!, encoding: String.Encoding.utf8)

            debugPrint("Notified.")
        }
    }
    
    func centralManager(_ central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: Error?) {
        debugPrint("Disconnected.")
        
        central.scanForPeripherals(withServices: nil, options: nil)
        
        // Hide respective user interface
    }
    
}