Connecting IOS app to Raspberry Pi 4 over bluetooth

Question

I created a new app with swiftUI and trying to use coreBluetooth library to connect Raspberry Pi 4. I searched all the google and I stuck at connecting Raspberry Pi 4. I can find all the devices (peripherals) but I'm not able to connect them.

Here is the code;

class BLEManager: NSObject, ObservableObject, CBCentralManagerDelegate {
    
    var myCentral: CBCentralManager!
    
    @Published var isSwitchedOn = false
    @Published var peripherals = [Peripheral]()
    
    override init() {
        super.init()

        myCentral = CBCentralManager(delegate: self, queue: nil)
        myCentral.delegate = self
    }
    
    func centralManagerDidUpdateState(_ central: CBCentralManager) {
        if central.state == .poweredOn {
            isSwitchedOn = true
        }
        else {
            isSwitchedOn = false
        }
    }
    
    func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
        var peripheralName: String!
       
        if let name = advertisementData[CBAdvertisementDataLocalNameKey] as? String {
            peripheralName = name
        }
        else {
            peripheralName = "Unknown"
        }
       
        if peripheral.identifier.uuidString == "6D915395-3E79-0072-22A3-009DDC331F7C" {
            myCentral.stopScan()
            myCentral.connect(peripheral, options: nil)
            print("okokokokok")
        }
        
        let newPeripheral = Peripheral(id: peripherals.count, name: peripheralName, rssi: RSSI.intValue)
        print(newPeripheral)
        peripherals.append(newPeripheral)
    }
    
    func centralManager(central: CBCentralManager!,didConnectPeripheral peripheral: CBPeripheral!)
    {
        peripheral.discoverServices(nil)
        print("Connected")
        print(peripheral.name!)
        print(peripheral.services!)
    }
    
}

Deleted some of code parts bc of stackoverfow

Answer 1

Your problem for the connection was not holding a reference to the CBPeripheral object to which you want to connect. So you've solved it by referencing to it in your BLEManager class.

Now how can you send and get data to / from your Raspberry? Well you must implement the CBPeripheralDelegate in your BLEManager class.

1. After the central manager finishes discovering the available services it will call didDiscoverServices method of CBPeripheralDelegate; where you need to invoke discoverCharacteristics for the discovered service.
2. Again, when characteristics has been discovered for the given service with the discoverCharacteristics(_:for:) method which you invoked in the didDiscoverServices callback, you can set the notify value if you want to know about characteristic updates.
3. After the characteristics has been discovered you can send values by using writeValue method of CBPeripheral instance to which you've referenced it when connected.
4. When you send data from the Raspberry for a certain charachteristic, the didUpdateValueFor method of CBPeripheralDelegate will get called. In this callback; you can obtain the received data from the CBCharacteristic.value property. Note that the value property is optional, hence you need to handle it with care.