TouchId FaceId login demo

效果图：

Views

LoginView.swift:

import SwiftUI

struct LoginView: View {
    @EnvironmentObject var authenticationManager: AuthenticationManager
    
    var body: some View {
        VStack(spacing: 40) {
            Title()
            
            switch authenticationManager.biometryType {
            case .faceID:
                PrimaryButton(image: "faceid", text: "Login with FaceID")
                    .onTapGesture {
                        Task.init {
                            await authenticationManager.authenticateWithBiometrics()
                        }
                    }
            case .touchID:
                PrimaryButton(image: "touchid", text: "Login with TouchID")
                    .onTapGesture {
                        Task.init {
                            await authenticationManager.authenticateWithBiometrics()
                        }
                    }
            default:
                NavigationLink {
                    CredentialsLoginView()
                        .environmentObject(authenticationManager)
                } label: {
                    PrimaryButton(image: "person.fill", text: "Login with your credentials")
                }
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(LinearGradient(colors: [.blue, .purple], startPoint: .topLeading, endPoint: .bottomTrailing))
    }
}

struct LoginView_Previews: PreviewProvider {
    static var previews: some View {
        LoginView()
            .environmentObject(AuthenticationManager())
    }
}

CredentialsLoginView.swift:

import SwiftUI

struct CredentialsLoginView: View {
    @EnvironmentObject var authenticationManager: AuthenticationManager
    @State private var username = ""
    @State private var password = ""
    
    var body: some View {
        VStack(spacing: 40) {
            Title()
            
            TextField("Username", text: $username)
            
            SecureField("Password", text: $password)
            
            PrimaryButton(showImage: false, text: "Login")
                .onTapGesture {
                    authenticationManager.authenticateWithCredentials(username: username, password: password)
                }
        }
        .textFieldStyle(.roundedBorder)
        .padding()
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(LinearGradient(colors: [.blue, .purple], startPoint: .topLeading, endPoint: .bottomTrailing))
    }
}

struct CredentialsLoginView_Previews: PreviewProvider {
    static var previews: some View {
        CredentialsLoginView()
            .environmentObject(AuthenticationManager())
    }
}

ContentView.swift:

import SwiftUI

struct ContentView: View {
    @StateObject var authenticationManager = AuthenticationManager()
    
    var body: some View {
        NavigationView {
            VStack {
                if authenticationManager.isAuthenticated {
                    VStack(spacing: 40) {
                        Title()
                        
                        Text("Welcome in! You are now authenticated.")
                            .foregroundColor(.white)
                        
                        PrimaryButton(showImage: false, text: "Logout")
                            .onTapGesture {
                                authenticationManager.logout()
                            }
                    }
                    .frame(maxWidth: .infinity, maxHeight: .infinity)
                    .background(LinearGradient(colors: [.blue, .purple], startPoint: .topLeading, endPoint: .bottomTrailing))
                } else {
                    LoginView()
                        .environmentObject(authenticationManager)
                }
            }
            .frame(maxWidth: .infinity, maxHeight: .infinity)
            .edgesIgnoringSafeArea(.all)
            .alert(isPresented: $authenticationManager.showAlert) {
                Alert(title: Text("Error"), message: Text(authenticationManager.errorDescription ?? "Error trying to login with credentials, please try again"), dismissButton: .default(Text("Ok")))
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Components

Title.swift:

import SwiftUI

struct Title: View {
    var body: some View {
        Text("Authenticator")
            .bold()
            .font(.title)
            .foregroundColor(.white)
    }
}

struct Title_Previews: PreviewProvider {
    static var previews: some View {
        Title()
            .background(LinearGradient(colors: [.blue, .purple], startPoint: .topLeading, endPoint: .bottomTrailing))
    }
}

PrimaryButton.swift:

import SwiftUI

struct PrimaryButton: View {
    var image: String?
    var showImage = true
    var text: String
    
    var body: some View {
        HStack {
            if showImage {
                Image(systemName: image ?? "person.fill")
            }
            
            Text(text)
        }
        .padding()
        .padding(.horizontal)
        .background(.white)
        .cornerRadius(30)
        .shadow(radius: 10)
    }
}

struct PrimaryButton_Previews: PreviewProvider {
    static var previews: some View {
        PrimaryButton(image: "faceid", text: "Login with FaceID")
    }
}

Authentication Manager

AuthenticationManager.swift:

import Foundation
import LocalAuthentication

class AuthenticationManager: ObservableObject {
    private(set) var context = LAContext()
    @Published private(set) var biometryType: LABiometryType = .none
    private(set) var canEvaluatePolicy = false
    @Published private(set) var isAuthenticated = false
    @Published private(set) var errorDescription: String?
    @Published var showAlert = false
    
    init() {
        getBiometryType()
    }
    
    func getBiometryType() {
        canEvaluatePolicy = context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: nil)
        biometryType = context.biometryType
    }
    
    func authenticateWithBiometrics() async {
        context = LAContext()
        
        if canEvaluatePolicy {
            let reason = "Log into your account"
            
            do {
                let success = try await context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason)
                
                if success {
                    DispatchQueue.main.async {
                        self.isAuthenticated = true
                        print("isAuthenticated", self.isAuthenticated)
                    }
                }
            } catch {
                print(error.localizedDescription)
                DispatchQueue.main.async {
                    self.errorDescription = error.localizedDescription
                    self.showAlert = true
                    self.biometryType = .none
                }
            }
        }
    }
    
    func authenticateWithCredentials(username: String, password: String) {
        if username.lowercased() == "stephanie" && password == "123456" {
            isAuthenticated = true
        } else {
            errorDescription = "Wrong credentials"
            showAlert = true
        }
    }
    
    func logout() {
        isAuthenticated = false
    }
}