Send informations with Bluetooth in Swift IOS language

Question

I'm actually in informatics school and I have some trouble with the connection between my own self signed app coded in Swift(Xcode 11.3 and for IOS 13.2 device) and a BLE module SH-HC-08 plugged on an Arduino. (UUID : FE60E626-C58C-69F5-324F-43C7C409A93D)

I'm totally new into swift language and self-learning this way of thinking in this language.

I'm using CoreBluetooth to detect if the Bluetooth on my iPhone is On or off. I can't actually check if my peripheral is detected, and can't send any information by my app. (don't understand how to configure the methods in CoreBluetooth)

I downloaded apps caled LightBlue and BluetoothLE on app store. The first one give me fews information about my Bluetooth device and the second one allow me to sends Ascii Strings to my Arduino by my Bluetooth module.

LightBlue information 1:

LightBlue information 2:

BluetoothLE app:

As I said before, i already :

Import CoreBluetooth
Add CBCentralManagerDelegate & CBPeripheralDelegate to my class ViewController
instantiate CBCentralManager and CBPeripheral
setup the centralManagerDidUpdateState function

CoreBluetooth code:

import UIKit
import CoreBluetooth



var texteEnvoyer:String?
var test = false



class ViewController: UIViewController, CBCentralManagerDelegate, CBPeripheralDelegate {
    
    var manager:CBCentralManager!
    var module : CBPeripheral!
    
    @IBOutlet weak var labelConnection: UILabel!
    @IBOutlet weak var switchConnection: UISwitch!
    @IBOutlet weak var labelTextField: UITextField!
    @IBOutlet weak var labelTest: UILabel!



    override func viewDidLoad() {
        super.viewDidLoad()
        
        refresh()
        manager = CBCentralManager(delegate: self, queue: nil)
        
        
    }
    
    
    func centralManagerDidUpdateState(_ central: CBCentralManager)
     {
         if(central.state == .poweredOff)
         {
            let alertController = UIAlertController(title: "Bluetooth", message: "Le bluetooth est déconnecté, veuillez l'activer et vous connecter au module.", preferredStyle: UIAlertController.Style.alert)
            alertController.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
            present(alertController, animated: true, completion: nil)
            test = false
         }
         if(central.state == .poweredOn)
         {
             test = true
         }
         refresh()
     }

I tried to play with the others methods like didDiscoverPeripheral or didConnected but I don't understand what i do and can't find any help to send information (preferred in String) by a self made application with bluetooth.

I tried that to discover my module but I don't have any "print" in my logs and don't know if my request was done or not... if I do it well or not too.

func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
        print("Name: \(peripheral.name)")
        self.module = peripheral
        self.module.delegate = self
        
        if(peripheral.name == "SG-HC-08"){
            manager.stopScan()
            manager.connect(self.module, options: nil)
            print(peripheral.name)
        }
    }

Someone have any experience with that or any help to give it will help me so much. Thanks

Julian Silvestri · Accepted Answer

Jikko,

I would be careful with using Global Variables.

Your global variables are the two declared outside of your class scope.

var texteEnvoyer:String? 
var test = false

These can sometimes cause issues with your program such as memory leaks and retention. Im not saying that this is the case for you. But if you continue to develop and publish applications this may be something to rethink. Im sure for your purposes now this is totally fine.

To your point of "nothing in the console form the peripheral" we can try adding in some print statements to help us debug what is actually happening.

For starters:

func centralManagerDidUpdateState(_ central: CBCentralManager){
   //.....
   print("ENTERED THE FUNCTION")
   if(peripheral.name == "SG-HC-08"){
        manager.stopScan()
        manager.connect(self.module, options: nil)
        print("REACHED HERE")
    }
}

IF in the console you see "REACHED HERE" then we know the code was called and executed. However this does not mean a successful connection.

If we do not see the print statement "ENTERED THE FUNCTION" , or "REACHED HERE" then that means there is a basic error. The function was never called or executed.

I would first create a function like so:

func startScan(){
  if let central = manager {
    central.scanForPeripheralsWithServices(nil, options: nil)
    print("started Scanning")
  }
}

And then in viewDidLoad() call the start scan

override func viewDidLoad(){
    super.viewDidLoad(animated)
    startScan()
}

And then once you have discovered a peripheral use the didDiscoverPeripheral method (which will be called first)

func centralManager(_ central: CBCentralManager!, didDiscoverPeripheral peripheral: CBPeripheral!, advertisementData: [NSObject : AnyObject]!, RSSI: NSNumber!) {
  print("DISCOVERED PERIPHERAL", peripheral)
  // manager.connectPeripheral(peripheral, options: nil)
}

You can then connect to it once discovered.

Hope this helps

EDIT ----

try adding in these two lines to your function.

   peripheral.delegate = self
   peripheral.discoverServices(nil)

like so

func centralManager(_ central: CBCentralManager!, didDiscoverPeripheral peripheral: CBPeripheral!, advertisementData: [NSObject : AnyObject]!, RSSI: NSNumber!) {
  print("DISCOVERED PERIPHERAL", peripheral)
  // manager.connectPeripheral(peripheral, options: nil)
}

I forgot to add in the underscore "_" to the function parameters

func centralManager(_ central: ....) {}

--------------------^

Send informations with Bluetooth in Swift IOS language

Answers (2)

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