How to convert type Data to string or uint8

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Created Apr ’21

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Hello,
I am reading the value of a characteristic sent from an Arduino (peripheral) via Bluetooth. However, when attempting to print the value, it only prints an empty string. I cannot even compare the value to another variable (integer or string) because it cannot be converted from type Data. I have tried turning it into a UTF8 (string), ascii string, etc. but nothing seems to be working.
Here is my code and some things I've tried:

Code Block import UIKit
import CoreBluetooth
//local central device object
class BluetoothViewController: UIViewController, CBPeripheralDelegate, CBCentralManagerDelegate {
    //properties
    private var centralManager: CBCentralManager!
    private var peripheral: CBPeripheral!
    
    //label to display stage of gait cycle
    @IBOutlet weak var StateLabel: UILabel!
    
    //characteristics
    private var StateVar: CBCharacteristic?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        centralManager = CBCentralManager(delegate: self, queue: nil)
    }
    
   //a bunch of core bluetooth functions connecting to peripheral and finding the Arduino's serivce...
    
    //handle discovery of characteristics... subscribe to notifications...
   
    
    //notification update
    func peripheral(_ peripheral: CBPeripheral, didUpdateNotificationStateFor characteristic: CBCharacteristic, error: Error?) {
       if let error = error {
            // Handle error
            print(error)
            return
       }
        // Successfully subscribed to or unsubscribed from notifications/indications on a characteristic
    }
    
    //read value
    func readValue(characteristic: CBCharacteristic) {
        self.peripheral.readValue(for: characteristic)
    }
    
    //value returned from readValue
    func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
        if let error = error {
            // Handle error
            print(error)
            return
        }
        //var charASCIIval = NSString()
        
        //guard let StateVar = characteristic.value else { return }
        guard let StateVar = characteristic.value,
              let stringFromData = String(data: StateVar, encoding: .utf8) else { return }
        
        //let stringVal = String(decoding: StateVar, as: UTF8.self)
        //let stringVal = "\u{StateVar}"
        //let stringVal = String(UnicodeScalar(StateVar))
        //let StateVar = string.StateVar(using: .utf8)
        print(stringFromData)
        StateLabel.text = stringFromData
        
        //if([readCBUUIDs containsObject: [ArduinoPeripheral.ArduinoCharacteristicUUID]])
        
        //let ASCIIstring = NSString(data: StateVar, encoding: String.Encoding.utf8.rawValue) //else { return }
        //charASCIIval = ASCIIstring
        
        //guard let StateVarInt = StateVar as? UInt8 else { return }
        
        //StateLabel.text = String(data: StateVar, encoding: String.Encoding.ascii)!
        
        //StateLabel.text = "Value updated"
        
        //let StateVar = StateVar as! UInt8
        
        //State machine
        if StateVar == 0 {
            StateLabel.text = "Leg Hold"
        }
        else if StateVar == 1 {
            StateLabel.text = "Swing"
        }
        else if StateVar == 2 {
            StateLabel.text = "Heel Step"
        }
        else if StateVar == 3 {
            StateLabel.text = "Drag Heel"
        }
        else if StateVar == 4 {
            StateLabel.text = "Toe Off"
        }
        else if StateVar == 5 {
            StateLabel.text = "Drag Toe"
        }
       else if StateVar == 6 {
           StateLabel.text = "Stance"
        }
       else if StateVar == 7 {
           StateLabel.text = "Drag All"
        }
       else if StateVar == 8 {
           StateLabel.text = "Leg Moving Backwards"
       }
    }
   // init<T> (_ source T) where T: BinaryInteger
   // init init(clamping:)
    
}

I would like to compare the value of the characteristic to a number (0-8) so I can output the correct stage of the gait cycle but I get the error:
Referencing operator function '==' on 'BinaryInteger' requires that 'Data' conform to 'BinaryInteger'

Please help!! Thank you!

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