বায়োমেট্রিক বা ফেসআইডি / টাচআইডি অথেনটিকেশন – iOS

import SwiftUI
import LocalAuthentication
 
class AuthManager: ObservableObject {
    @Published var username: String = "admin"
    @Published var password: String = "123456"
     
    @Published var isAuthenticated = false
    @Published var errorMessage: String?
     
    func loginWithFaceID() async{
        let context = LAContext()
        let reason = "Log into your account"
        do {
            // Check if Face ID is available
            let success = try await context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason)
            if success{
                // If user authenticated using faceID, login.
                await fakeLogin()
            }
        } catch {
            // No biometric authentication available
            DispatchQueue.main.async{
                self.errorMessage = error.localizedDescription
            }
        }
    }
    func fakeLogin() async{
        // for now, we will check the credential from hardcoded data.
        if username.lowercased() == "admin" && password == "123456" {
            DispatchQueue.main.async{
                self.isAuthenticated = true
            }
        } else {
            DispatchQueue.main.async{
                self.errorMessage = "Wrong Credentials"
            }
        }
    }

import SwiftUI
 
struct ContentView: View {
    @StateObject private var authManager = AuthManager()
     
    var body: some View {
        VStack {
            if authManager.isAuthenticated {
                Text("Welcome, you are authenticated!")
                    .font(.title)
                Button(action: {
                    authManager.logout()
                }, label: {
                    Label("Logout", systemImage: "arrow.backward.circle")
                })
                .font(.title)
                 
            } else {
                Button(action: {
                    Task{
                        await   authManager.loginWithFaceID()
                    }
                }, label: {
                    Label("Login with Face ID", systemImage: "faceid")
                })
                .font(.title)
                 
                if let errorMessage = authManager.errorMessage {
                    Text(errorMessage)
                        .foregroundColor(.red)
                        .padding()
                }
            }
        }
        .padding()
    }
}
 
 
#Preview {
    ContentView()
}

import Security
 
func saveToKeychain(service: String, account: String, data: Data) -> Bool {
    func saveToKeychain(service: String, account: String, data: Data) -> Bool {
        let query = [
            kSecClass: kSecClassGenericPassword,
            kSecAttrService: service,
            kSecAttrAccount: account,
            kSecValueData: data
        ] as CFDictionary
         
        // Delete any existing items
        SecItemDelete(query)
         
        // Add new keychain item
        let status = SecItemAdd(query, nil)
        return status == errSecSuccess
    }
     
     
    func retrieveFromKeychain(service: String, account: String) -> Data? {
        let query = [
            kSecClass: kSecClassGenericPassword,
            kSecAttrService: service,
            kSecAttrAccount: account,
            kSecReturnData: true,
            kSecMatchLimit: kSecMatchLimitOne
        ] as CFDictionary
         
        var result: AnyObject?
        let status = SecItemCopyMatching(query, &result)
         
        if status == errSecSuccess {
            return result as? Data
        } else {
            return nil
        }
    }

import SwiftUI
import LocalAuthentication
 
import Security
 
class AuthManager: ObservableObject {
    @AppStorage("username") var username = ""
    @Published var password: String = ""
    @Published var service = "com.yourapp.service"
     
    @Published var isAuthenticated = false
    @Published var errorMessage: String?
     
    func biometricLogin() async{
        let context = LAContext()
        let reason = "Log into your account"
        do {
            // Check if Face ID is available
            let success = try await context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason)
            if success{
                self.retrieveCredentialsAndLogin()
            } else {
                DispatchQueue.main.async{
                    self.errorMessage =  "Try to login using credential first."
                }
            }
        } catch {
            // No biometric authentication available
            DispatchQueue.main.async{
                self.errorMessage = error.localizedDescription
            }
        }
    }
 
    func credentialLogin() async{
        // for now, we will check the credential from hardcoded data.
        if username.lowercased() == "admin" && password == "123456" {
            DispatchQueue.main.async{
                // store credential to keychain
                _ = self.saveToKeychain(service: self.service, account: self.username, data: Data(self.password.utf8))
                self.isAuthenticated = true
                self.errorMessage = ""
            }
        } else {
            DispatchQueue.main.async{
                self.errorMessage = "Wrong Credentials."
            }
        }
    }
     
 
    private func retrieveCredentialsAndLogin() {
         
        if let passwordData = retrieveFromKeychain(service: service, account: username),
           let retrievePassword = String(data: passwordData, encoding: .utf8) {
            if username.lowercased() == "admin" && retrievePassword == "123456" {
                DispatchQueue.main.async{
                    self.isAuthenticated = true
                    self.errorMessage = ""
                }
            }else {
                DispatchQueue.main.async{
                    self.errorMessage = "Wrong Credentials."
                }
            }
        } else {
            self.errorMessage = "Failed to retrieve credentials."
        }
    }
     
     
    func saveToKeychain(service: String, account: String, data: Data) -> Bool {
        let query = [
            kSecClass: kSecClassGenericPassword,
            kSecAttrService: service,
            kSecAttrAccount: account,
            kSecValueData: data
        ] as CFDictionary
         
        // Delete any existing items
        SecItemDelete(query)
         
        // Add new keychain item
        let status = SecItemAdd(query, nil)
        return status == errSecSuccess
    }
     
     
    func retrieveFromKeychain(service: String, account: String) -> Data? {
        let query = [
            kSecClass: kSecClassGenericPassword,
            kSecAttrService: service,
            kSecAttrAccount: account,
            kSecReturnData: true,
            kSecMatchLimit: kSecMatchLimitOne
        ] as CFDictionary
         
        var result: AnyObject?
        let status = SecItemCopyMatching(query, &result)
         
        if status == errSecSuccess {
            return result as? Data
        } else {
            return nil
        }
    }
     
    func logout(){
        isAuthenticated = false
    }
}

import SwiftUI
 
struct ContentView: View {
    @StateObject private var authManager = AuthManager()
     
    var body: some View {
        VStack {
            if authManager.isAuthenticated {
                Text("Welcome, you are authenticated!")
                    .font(.title)
                Button(action: {
                    authManager.logout()
                }, label: {
                    Label("Logout", systemImage: "arrow.backward.circle")
                })
                .font(.title)
                 
            } else {
                VStack(spacing: 40){
                    TextField("Username", text: $authManager.username)
                    SecureField("Password", text: $authManager.password)
                    Button("Login with Credential") {
                        Task{
                            await authManager.credentialLogin()
                        }
                    }
                    Button("Login with FaceID / TouchID") {
                        Task{
                            await authManager.biometricLogin()
                        }
                    }
                    if let errorMessage = authManager.errorMessage {
                        Text(errorMessage)
                            .foregroundColor(.red)
                            .padding()
                    }
                }
                .textFieldStyle(.roundedBorder)
                .font(.title)
            }
        }
        .padding()
    }
}

#Preview {
    ContentView()
}