Updating code to Swift 3

I am a beginner to programming with swift and programming in general. I am currently working on an app which allows one phone to send a message (peripheral) to another which will receive the message (central). I have taken most of the code from an app built using swift 2 and have tweaked it slightly to remove any errors. As a result, my code is a jumble of swift 2/3 (or so I have been told). I am not sure how to update this code fully to swift 3 which I need someones help to do. I believe it is the IBActions and delegates that are outdated but I am completely clueless on how to amend it.

I have tried running the app and it runs successfully but when I press any of the buttons nothing happens as far as I can tell. I have a basic understanding of what my code does and what each function is there for but I find myself stuck on what to do for it to work. If anyone has experience working with Bluetooth via swift and can see what I am doing wrong or perhaps if I haven't included something important. I am led to believe the issue is that all the code has not been updated to swift 3 but I can't be sure. I have read the Apple documentation for Core bluetooth.

PS: I know this question is very vague as I am unsure on what part of my code I need to fix so it is very difficult to make it specific to a single issue. Sorry!

import UIKit import CoreBluetooth class ViewController: UIViewController, CBPeripheralManagerDelegate, CBCentralManagerDelegate, CBPeripheralDelegate { let messageUUID = CBUUID(string: "053D6600-821E-46A7-AC25-43A81D948E8B") let inputUUID = CBUUID(string: "49A79D26-5323-4374-81EA-29B099AF85C8") let otherUUID = CBUUID(string: "053D6600-821E-46A7-AC25-43A81D948E87") var peripheralManager: CBPeripheralManager! var characteritic: CBMutableCharacteristic! var getDataPeripheralCharacteristic: CBMutableCharacteristic! var service: CBMutableService! var outputData:String = "" var centralManager: CBCentralManager! var connectingPeripheral: CBPeripheral? var centralWriteCharacteristic: CBCharacteristic! @IBOutlet var inputLabel: UITextField! @IBOutlet weak var outputLabel: UILabel! override func viewDidLoad() { super.viewDidLoad() } @IBAction func centralMode(_ sender: UIButton) { centralManager = CBCentralManager(delegate: self, queue: nil) peripheralManager = nil } @IBAction func peripheralMode(_ sender: UIButton) { peripheralManager = CBPeripheralManager(delegate: self, queue: nil) centralManager = nil } @IBAction func sendData(_ sender: UIButton) { if (peripheralManager != nil) { let passed = peripheralManager.updateValue(inputLabel.text!.data(using: String.Encoding.utf8)!, for: characteritic!, onSubscribedCentrals: nil) if passed == false { print("error couldn't send data") } } if (centralManager != nil) { if (connectingPeripheral != nil) { connectingPeripheral?.writeValue(inputLabel.text!.data(using: String.Encoding.utf8)!, for: centralWriteCharacteristic, type: CBCharacteristicWriteType.withResponse) } } } func peripheralManagerDidUpdateState(_ peripheral: CBPeripheralManager) { if (peripheral.state == .poweredOn) { characteritic = CBMutableCharacteristic(type: messageUUID, properties: CBCharacteristicProperties.notify, value: nil, permissions: CBAttributePermissions.readable) getDataPeripheralCharacteristic = CBMutableCharacteristic(type: inputUUID, properties: CBCharacteristicProperties.write, value: nil, permissions: CBAttributePermissions.writeable) service = CBMutableService(type: otherUUID, primary: true) service.characteristics = [characteritic!, getDataPeripheralCharacteristic!] peripheralManager!.add(service) } } func peripheralManager(peripheral: CBPeripheralManager, didAddService service: CBService, error: NSError?) { peripheral.stopAdvertising() let identifier = Bundle.main.bundleIdentifier! let manufacturerData = identifier.data(using: String.Encoding.utf8, allowLossyConversion: false) let dataToBeAdvertised:[String: Any] = [ CBAdvertisementDataLocalNameKey : "Sample peripheral", CBAdvertisementDataManufacturerDataKey : manufacturerData as Any, CBAdvertisementDataServiceUUIDsKey : [messageUUID, inputUUID], ] peripheralManager.startAdvertising(dataToBeAdvertised) } func peripheralManager(peripheral: CBPeripheralManager, didReceiveWriteRequests requests: [CBATTRequest]) { for request in requests { if (request.characteristic.uuid.uuidString == inputUUID.uuidString) { outputData = String(data: request.value!, encoding: String.Encoding.utf8)! outputLabel.text = outputData } } } func peripheralManager(peripheral: CBPeripheralManager, didReceiveReadRequest request: CBATTRequest) { } func peripheralManager(peripheral: CBPeripheralManager, central: CBCentral, didSubscribeToCharacteristic characteristic: CBCharacteristic) { outputLabel.text = "Press send message" print("Now connected") } func centralManagerDidUpdateState(_ central: CBCentralManager) { if central.state == .poweredOn { centralManager.scanForPeripherals(withServices: nil, options: nil) //search for peripheral device } } //when peripheral is discovered, this method is called private func centralManager(central: CBCentralManager, didDiscoverPeripheral peripheral: CBPeripheral, advertisementData: [String : AnyObject], RSSI: NSNumber) { self.centralManager.stopScan(); self.connectingPeripheral = peripheral; peripheral.delegate = self; centralManager.connect(peripheral, options: nil) } //if connection request from central is succesfull, this method is called func centralManager(central: CBCentralManager, didConnectPeripheral peripheral: CBPeripheral) { peripheral.delegate = self; peripheral.discoverServices(nil) } //if central discovers services, this method is called private func peripheral(peripheral: CBPeripheral, didDiscoverServices error: NSError?) { for service: CBService in peripheral.services! { peripheral.discoverCharacteristics(nil, for: service) } } private func peripheral(peripheral: CBPeripheral, didDiscoverCharacteristicsForService service: CBService, error: NSError?) { if (service.uuid.uuidString == otherUUID.uuidString) { guard let characteristics = service.characteristics else { return } for characteristic in characteristics { if characteristic.uuid.uuidString == messageUUID.uuidString { peripheral.setNotifyValue(true, for: characteristic) } else if characteristic.uuid.uuidString == inputUUID.uuidString { centralWriteCharacteristic = characteristic } } } } private func peripheral(peripheral: CBPeripheral, didUpdateValueForCharacteristic characteristic: CBCharacteristic, error: NSError?) { if error != nil { print("Error reading characteristics"); } if (characteristic.uuid == messageUUID) { outputData = String(data: characteristic.value!, encoding: String.Encoding.utf8)! print(outputData) outputLabel.text = outputData } } }