Biometrics

BiometricsUtils.swift

import UIKit
import LocalAuthentication

class BiometricsUtils {

    //Should not be singleton as always success after first time checked
    //static let shared: BiometricsUtils = .init()
    
    private lazy var context = LAContext()
    
    init() {
        _ = askBiometricAvailability() //then get context.biometryType
    }
    
    var bioType: LABiometryType {
        context.biometryType
    }
    
    var availability: Bool {
        bioType == .faceID || bioType == .touchID
    }
    
    func askBiometricAvailability() -> (Bool, NSError?) {
        var error : NSError?
        let result = context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error)
        return (result, error)
    }
    /// Must call after viewDidAppear or will block viewDidLoad
    func authenticate(completion : @escaping (Result<Bool, LAError>) -> Void){
        Task {
            do {
                try await context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: "Log in to your wallet")
                await MainActor.run {
                    completion(.success(true))
                }
            } catch {
                await MainActor.run {
                    if let error = error as? LAError {
                        switch error.code {
                        case .biometryNotAvailable:
                            UIAlertController.showAlert(
                                withTitle: "Biometry Not Available",
                                message: "Open in setting?",
                                buttonTexts: [
                                    R.string.localizable.buttonYes(preferredLanguages: .currentLang),
                                    R.string.localizable.buttonNo(preferredLanguages: .currentLang)
                                ],
                                action: { index in
                                    if index == 0 {
                                        UIApplication.shared.open(
                                            URL(string: UIApplication.openSettingsURLString)!,
                                            options: [:],
                                            completionHandler: nil
                                        )
                                        completion(.failure(error))
                                    } else { // Absolutelly no
                                        completion(.success(false))
                                    }
                                }
                            )
                        default:
                            completion(.failure(error))
                            println(error.localizedDescription)
                        }
                    }
                }
            }
        }

    }

}