WebAuthn passkey on iOS

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import AuthenticationServices
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import SwiftUI
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// MARK: - Configuration Constants
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let const_baseUrl = "https://example.com" // Set your backend authentication URL here
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let const_scheme = "mgpsca" // Your custom URL scheme
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let const_returnParam = "&returnUrl=\(const_scheme)://auth" // Return URL for backend to redirect after authentication
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struct ContentView: View {
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    @State private var asPresentationContext: PresentationContextProvider? = nil
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    /// Starts the web authentication session
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    func startAuthentication() {
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        let strUrl = const_baseUrl + const_returnParam
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        guard let authURL = URL(string: strUrl) else {
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            print("Invalid URL")
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            return
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        }
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        let callbackScheme = const_scheme
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        let authSession = ASWebAuthenticationSession(
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            url: authURL,
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            callbackURLScheme: callbackScheme
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        ) { callbackURL, error in
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            // This closure is called when authentication completes or fails
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            if let error = error {
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                // Handle authentication error (e.g., user cancelled, network error)
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                print("Authentication failed with error: \(error.localizedDescription)")
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                return
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            }
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            guard let callbackURL = callbackURL else {
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                // No callback URL means authentication did not complete
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                print("No callback URL received")
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                return
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            }
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            // Handle the callback URL received from the authentication flow
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            handleIncomingURL(callbackURL)
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        }
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        // Provide presentation context so the session knows where to present the web browser
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        asPresentationContext = PresentationContextProvider()
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        authSession.presentationContextProvider = asPresentationContext
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        // Use ephemeral session to avoid sharing cookies with Safari (incognito-like)(no Pop-up)
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        authSession.prefersEphemeralWebBrowserSession = true
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        // Start the authentication session
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        authSession.start()
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    }
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    /// Handles the URL returned from the authentication flow
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    func handleIncomingURL(_ url: URL) {
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        print("Incoming URL: \(url)")
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        // Ensure the URL uses the expected custom scheme
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        guard let scheme = url.scheme, scheme == const_scheme else {
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            print("Invalid URL scheme")
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            return
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        }
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        // Parse the URL into components to extract query parameter
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        guard let components = URLComponents(url: url, resolvingAgainstBaseURL: true) else {
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            print("Invalid URL components")
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            return
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        }
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        guard let queryItems = components.queryItems else {
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            print("No query items found")
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            return
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        }
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        // Extract authentication status from query parameter
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        let controlStatusValue = queryItems.first(where: { $0.name == "controlStatus" })?.value ?? ""
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        // Check if authentication was successful
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        if controlStatusValue == "VALIDATED" {
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            print("SCA succeeded")
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        } else {
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            // Handle authentication failure or unexpected status
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            print("SCA failed : \(queryItems)")
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        }
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    }
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}
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// MARK: - Presentation Context Provider for ASWebAuthenticationSession
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/// Provides the presentation anchor (window) for ASWebAuthenticationSession
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class PresentationContextProvider: NSObject, ASWebAuthenticationPresentationContextProviding {
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    func presentationAnchor(for session: ASWebAuthenticationSession) -> ASPresentationAnchor {
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        if let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
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           let window = windowScene.windows.first {
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            return window
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        }
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        return ASPresentationAnchor()
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    }
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}