Here is my iOS bluetooth smartphone application code for the main view controller:

import UIKit

import CoreBluetooth

let heartRateServiceCBUUID = CBUUID(string: "0x180D")

let heartRateMeasurementCharacteristicCBUUID = CBUUID(string: "2A37")

let bodySensorLocationCharacteristicCBUUID = CBUUID(string: "2A38")

extension ViewController: CBCentralManagerDelegate {

func centralManagerDidUpdateState(_ central: CBCentralManager) {

switch central.state {

case .unknown:

print("central.state is .unknown")

case .resetting:

print("central.state is .resetting")

case .unsupported:

print("central.state is .unsupported")

case .unauthorized:

print("central.state is .unauthorized")

case .poweredOff:

print("central.state is .poweredOff")

case .poweredOn:

print("central.state is .poweredOn")

centralManager.scanForPeripherals(withServices: [heartRateServiceCBUUID])

}

}

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

print(peripheral)

heartRatePeripheral = peripheral

///heartRatePeripheral.delegate = self

centralManager.stopScan()

centralManager.connect(heartRatePeripheral)

}

func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {

func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {

print("Connected!")

heartRatePeripheral.discoverServices([heartRateServiceCBUUID])

}

}

}

class ViewController: UIViewController {

var centralManager: CBCentralManager!

var heartRatePeripheral: CBPeripheral!

override func viewDidLoad() {

super.viewDidLoad()

// Do any additional setup after loading the view, typically from a nib.

centralManager = CBCentralManager(delegate: self, queue: nil)

}

override func didReceiveMemoryWarning() {

super.didReceiveMemoryWarning()

// Dispose of any resources that can be recreated.

}

}

I have another view controller page that sends values when buttons are pushed to the bluetooth chip. Here is the code for that:

import UIKit

import CoreBluetooth

class TemperatureViewController: UIViewController {

var _peripheral: CBPeripheral?

var _characteristics: [CBCharacteristic]?

func peripheral(peripheral: CBPeripheral, didDiscoverCharacteristicsForService service: CBService, error:NSError?)

{

print("Found \(service.characteristics!.count) characteristics!: \(String(describing: service.characteristics))")

_peripheral = peripheral

_characteristics = service.characteristics

let string = "0"

let data = string.data(using: String.Encoding.utf8)

for characteristic in service.characteristics as [CBCharacteristic]!

{

if(characteristic.uuid.uuidString == "2A38")

{

print("sending data")

peripheral.writeValue(data!, for: characteristic,type: CBCharacteristicWriteType.withoutResponse)

}

}

}

@IBAction func offButtonTouch(_ sender: UIButton) {

var value: UInt8 = 0

let data = NSData(bytes: &value, length: MemoryLayout.size)

for characteristic in _characteristics as [CBCharacteristic]!

{

if(characteristic.uuid.uuidString == "2A38")

{

func writeValue(_ data: Data, for characteristic: CBCharacteristic,type:CBCharacteristicWriteType){

}

}

}

}

@IBAction func lowButtonTouch(_ sender: UIButton) {

var value: UInt8 = 1

let data = NSData(bytes: &value, length: MemoryLayout.size)

for characteristic in _characteristics as [CBCharacteristic]!

{

if(characteristic.uuid.uuidString == "2A38")

{

func writeValue(_ data: Data, for characteristic: CBCharacteristic,type:CBCharacteristicWriteType){

}

}

}

}

@IBAction func highButtonTouch(_ sender: UIButton) {

var value: UInt8 = 2

let data = NSData(bytes: &value, length: MemoryLayout.size)

for characteristic in _characteristics as [CBCharacteristic]!

{

if(characteristic.uuid.uuidString == "2A38")

{

func writeValue(_ data: Data, for characteristic: CBCharacteristic,type:CBCharacteristicWriteType){

}

}

}

}

}

Why does the app automatically send a 2 when the connection is made?