How to use TouchID in iOS 10

Question

I want to implement local authentication security in my iOS app but I'm getting an error and not able to figure out why I'm getting this.

I'm using iPhone 5s. Is that matters?

Code:

import UIKit
import LocalAuthentication

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func action(_ sender: Any) {
        authenticateUser()
    }

    func authenticateUser() {
        let authContext : LAContext = LAContext()
        var error: NSError?

        if authContext.canEvaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, error: &error){
            authContext.evaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, localizedReason: "Biometric Check for application", reply: {(successful: Bool, error: NSError?) -> Void in
                if successful{
                    print("TouchID Yes")
                }
                else{
                    print("TouchID No")
                }
                } as! (Bool, Error?) -> Void)
        }
        else{
            authContext.evaluatePolicy(LAPolicy.deviceOwnerAuthentication, localizedReason: "Enter your Passcode", reply: {
                (successful: Bool, error: NSError?) in
                if successful{
                    print("PassCode Yes")
                }
                else{
                    print("PassCode No")
                }
                } as! (Bool, Error?) -> Void)
        }
    }
}

Error:

Thanks in advance.

Answer 1

This code without typecasting should work

func authenticateUser() {
    let authContext : LAContext = LAContext()
    var error: NSError?

    if authContext.canEvaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, error: &error){
        authContext.evaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, localizedReason: "Biometric Check for application", reply: {successful, error -> Void in
            if successful{
                print("TouchID Yes")
            }
            else{
                print("TouchID No")
            }
        }
        )
    }
    else{
        authContext.evaluatePolicy(LAPolicy.deviceOwnerAuthentication, localizedReason: "Enter your Passcode", reply: {
            successful,error in
            if successful{
                print("PassCode Yes")
            }
            else{
                print("PassCode No")
            }
        }
        )
    }
}