Resolving Instagram Login Issues with ASWebAuthenticationSession in Swift

Handling Instagram Login in Swift with ASWebAuthenticationSession

This solution uses SwiftUI and Apple's AuthenticationServices framework for handling Instagram login issues.

import SwiftUI
import AuthenticationServices

struct InstagramLoginView: View {
    @State private var authSession: ASWebAuthenticationSession?
    @State private var token: String = ""
    @State private var showAlert: Bool = false
    @State private var alertMessage: String = ""

    var body: some View {
        VStack {
            Text("Instagram Login")
                .font(.largeTitle)
                .padding()

            Button(action: { startInstagramLogin() }) {
                Text("Login with Instagram")
                    .padding()
                    .background(Color.blue)
                    .foregroundColor(.white)
                    .cornerRadius(10)
            }

            if !token.isEmpty {
                Text("Token: \(token)")
                    .padding()
            }
        }
        .alert(isPresented: $showAlert) {
            Alert(title: Text("Error"),
                  message: Text(alertMessage),
                  dismissButton: .default(Text("OK")))
        }
    }

    func startInstagramLogin() {
        let clientID = "XXXXXXXXXX"
        let redirectURI = "https://example.com"

        guard let authURL = URL(string:
            "https://api.instagram.com/oauth/authorize?client_id=\(clientID)&redirect_uri=\(redirectURI)&scope=user_profile,user_media&response_type=code"
        ) else {
            alertMessage = "Invalid URL"
            showAlert = true
            return
        }

        authSession = ASWebAuthenticationSession(url: authURL, callbackURLScheme: nil) { callbackURL, error in
            if let error = error {
                alertMessage = error.localizedDescription
                showAlert = true
                return
            }

            guard let callbackURL = callbackURL else {
                alertMessage = "Invalid callback URL"
                showAlert = true
                return
            }

            if let code = URLComponents(string: callbackURL.absoluteString)?.queryItems?.first(where: { $0.name == "code" })?.value {
                getInstagramAccessToken(authCode: code)
            }
        }
        authSession?.presentationContextProvider = self
        authSession?.start()
    }

    func getInstagramAccessToken(authCode: String) {
        let tokenURL = "https://api.instagram.com/oauth/access_token"
        var request = URLRequest(url: URL(string: tokenURL)!)
        request.httpMethod = "POST"

        let clientID = "XXXXXXXXXX"
        let clientSecret = "XXXXXXXXXX"
        let redirectURI = "https://example.com"

        let params = "client_id=\(clientID)&client_secret=\(clientSecret)&grant_type=authorization_code&redirect_uri=\(redirectURI)&code=\(authCode)"
        request.httpBody = params.data(using: .utf8)
        request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")

        URLSession.shared.dataTask(with: request) { data, response, error in
            if let error = error {
                alertMessage = error.localizedDescription
                showAlert = true
                return
            }

            guard let data = data else {
                alertMessage = "No data received"
                showAlert = true
                return
            }

            if let jsonResponse = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
               let accessToken = jsonResponse["access_token"] as? String {
                DispatchQueue.main.async { token = accessToken }
            } else {
                alertMessage = "Failed to get access token"
                showAlert = true
            }
        }.resume()
    }
}

extension InstagramLoginView: ASWebAuthenticationPresentationContextProviding {
    func presentationAnchor(for session: ASWebAuthenticationSession) -> ASPresentationAnchor {
        UIApplication.shared.windows.first { $0.isKeyWindow }!
    }
}

Implementing Django for Redirect URI Validation

This script uses Django as a backend to validate Instagram OAuth callbacks and handle tokens securely.

from django.http import JsonResponse, HttpResponseRedirect
from django.views.decorators.csrf import csrf_exempt
import requests

CLIENT_ID = 'XXXXXXXXXX'
CLIENT_SECRET = 'XXXXXXXXXX'
REDIRECT_URI = 'https://example.com/callback'

@csrf_exempt
def instagram_callback(request):
    code = request.GET.get('code')
    if not code:
        return JsonResponse({'error': 'Missing authorization code'})

    token_url = 'https://api.instagram.com/oauth/access_token'
    payload = {
        'client_id': CLIENT_ID,
        'client_secret': CLIENT_SECRET,
        'grant_type': 'authorization_code',
        'redirect_uri': REDIRECT_URI,
        'code': code
    }

    response = requests.post(token_url, data=payload)
    if response.status_code == 200:
        return JsonResponse(response.json())
    return JsonResponse({'error': 'Failed to retrieve access token'})

Common Questions About Instagram Login with ASWebAuthenticationSession

1. What is the purpose of ASWebAuthenticationSession?
2. ASWebAuthenticationSession provides a secure way to authenticate users through web-based flows like OAuth in iOS applications.
3. Why does Instagram not support custom URL schemes?
4. Instagram prioritizes universal links or HTTPS-based redirect URIs for security and compatibility with their OAuth implementation.
5. How do I handle the "Error: The operation couldn’t be completed" issue?
6. Ensure your callbackURLScheme matches the URL defined in your app's configuration and Instagram’s redirect URI.
7. What is the role of presentationContextProvider?
8. presentationContextProvider specifies where the web authentication session UI is displayed, linking it to the app’s window.
9. Can I test Instagram login locally?
10. While testing locally is limited, you can use tools like ngrok to expose your local backend to Instagram for redirect URI testing.
11. Is it mandatory to use a backend for Instagram login?
12. Using a backend is highly recommended as it handles secure token exchanges and manages sensitive data like client secrets.
13. How do I validate the authorization code?
14. Send the code to Instagram’s token endpoint with URLSession in Swift or requests in Python for validation.
15. Why is my token request failing?
16. Double-check your client ID, client secret, and ensure the redirect URI matches exactly what is configured on Instagram.
17. Can I reuse the code examples provided?
18. Yes, the scripts are modular and can be adapted to other OAuth providers with minimal changes.
19. How do I handle user sessions after login?
20. Store tokens securely using Keychain in iOS or encrypted storage on the backend to maintain user sessions.

Best Practices for Instagram Login Flow

To successfully implement Instagram login using ASWebAuthenticationSession, it's crucial to ensure the callback URL matches the one configured in Instagram's app settings. Instagram does not allow custom schemes for authentication, so your app must use a secure, publicly accessible redirect URI. Additionally, handling errors like "Error: The operation couldn’t be completed" requires validating URL components and handling the authentication flow carefully. Pay attention to the session's context provider, ensuring the authentication flow works on the active window and the user is redirected correctly after login.

Testing is an important step, as local configurations might not always behave as expected. Consider deploying your backend and using tools like ngrok to expose local services for testing. With careful attention to security practices and clear handling of authentication tokens, your Instagram login implementation will be more reliable. These steps ensure users can authenticate smoothly and securely without encountering errors during the OAuth process. 🚀