Implementing OAuth 2.0 for User Authentication in an iOS App - Unique Scenarios and Challenges
I'm stuck on something that should probably be simple... I'm integrating two systems and I tried several approaches but none seem to work... Currently developing an iOS application that requires user authentication via OAuth 2.0. I’ve chosen to use the **AppAuth** library due to its popularity and comprehensive documentation. The project is built in Swift, and I'm targeting iOS 15 and later. The goal is to authenticate users with Google and fetch their profile data post-login. I started by integrating the AppAuth library with CocoaPods: ```ruby pod 'AppAuth', '~> 1.4' ``` Next, I set up the configuration for OAuth, which looks something like this: ```swift let issuer = URL(string: "https://accounts.google.com")! let redirectUri = URL(string: "com.example.app:/oauth2redirect")! let clientId = "YOUR_CLIENT_ID" let clientSecret = "YOUR_CLIENT_SECRET" ``` After constructing the authorization request, I used the following code: ```swift let request = OIDAuthorizationRequest(configuration: configuration, clientId: clientId, clientSecret: clientSecret, scopes: [OIDScopeOpenID, OIDScopeProfile], redirectURL: redirectUri, responseType: OIDResponseTypeCode, additionalParameters: nil) ``` However, I’m struggling with the redirect process. When the user logs in, the response is supposed to redirect back to my app, but I’m getting an error: **"Invalid redirect URI"**. I’ve ensured that the redirect URI matches what’s set in the Google Developer Console, yet the problem persists. I’ve also tried to debug using the `OIDAppDelegate` to handle the callback, but the delegate method isn’t being called. Here’s how I set it up: ```swift func application(_ application: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey: Any] = [:]) -> Bool { return OIDAppAuth.sharedInstance().resumeAuthorizationFlow(with: url) } ``` Beyond the redirect issue, I need to handle the access token and refresh it appropriately. After the user logs in, I want to make a request to fetch their profile, but I’m unsure how to manage token expiration gracefully. Is there a best practice for storing tokens securely on iOS? Using the **Keychain** seems like a solid approach, but I'm also considering how to refresh the token using the refresh token flow. Any insights on optimizing this part would be greatly appreciated. I’m really looking to implement this securely and efficiently, adhering to best practices while avoiding common pitfalls in OAuth 2.0. How would you solve this? The stack includes Swift and several other technologies. This is part of a larger REST API I'm building. I'd really appreciate any guidance on this.