Swift开发问题：IBOutlet连接断开及Firebase Gmail登录按钮异常

Hey there! Let's work through your two Swift development problems one at a time—they’re both super common, so we’ve got this!

If your button’s IBOutlet keeps disconnecting after building, try these targeted fixes:

• Double-check your view controller’s Custom Class in the Storyboard’s Identity Inspector. Make sure the class name is spelled correctly, and the module is set to your project (not "None"—this is a frequent culprit when working with CocoaPods dependencies).
• Hunt down duplicate or stale connections: Right-click the button in Storyboard, open the Connections Inspector, and delete any old/duplicate references to your IBOutlet. You can also right-click your view controller class file in the Project Navigator and check the Connections panel to remove invalid links.
• Clear your project’s cache: Hit Cmd + Shift + K to clean the build folder, then Cmd + Option + Shift + K to wipe derived data. Restart Xcode after this—sometimes old cached data causes weird connection glitches.
• Avoid mismatched names: If you rename the IBOutlet variable in code, don’t forget to update the connection in Storyboard. It’s often easier to just delete the old connection and re-drag from the button to your code file.
• Check if the button’s parent view is accidentally hidden or removed: If the button’s superview is set to isHidden = true or gets removed from the hierarchy, Xcode might drop the connection as it thinks the button isn’t active.

Let’s fix the GIDSignInButton subclass issue and get your Google login working smoothly:

First, rule out dependency issues #

Make sure you’ve properly installed Firebase and GoogleSignIn. If you’re using CocoaPods, your Podfile should include:

pod 'Firebase/Auth'
pod 'GoogleSignIn'

Run pod install and open the .xcworkspace file (not the .xcodeproj—this is a common mistake that breaks framework links!).

Option 1: Create the button with code (more reliable) #

Skip Storyboard altogether for this button—code-based setup avoids subclass bugs entirely:

import UIKit
import GoogleSignIn
import FirebaseAuth

class LoginViewController: UIViewController, GIDSignInDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Create and position the Google Sign-In button
        let signInButton = GIDSignInButton()
        signInButton.frame = CGRect(x: 20, y: 300, width: view.frame.width - 40, height: 50)
        view.addSubview(signInButton)
        
        // Configure Google Sign-In
        GIDSignIn.sharedInstance().delegate = self
        GIDSignIn.sharedInstance().presentingViewController = self
        // Optional: Auto-sign in if user was previously logged in
        GIDSignIn.sharedInstance().restorePreviousSignIn()
    }
    
    // Handle Google Sign-In result
    func sign(_ signIn: GIDSignIn!, didSignInFor user: GIDGoogleUser!, withError error: Error!) {
        if let error = error {
            print("Google Sign-In failed: \(error.localizedDescription)")
            return
        }
        
        // Pass Google credentials to Firebase
        guard let auth = user.authentication else { return }
        let credential = GoogleAuthProvider.credential(withIDToken: auth.idToken, accessToken: auth.accessToken)
        
        Auth.auth().signIn(with: credential) { [weak self] result, error in
            guard let self = self else { return }
            if let error = error {
                print("Firebase authentication failed: \(error.localizedDescription)")
                return
            }
            // Success! Navigate to your main app screen here
        }
    }
}

Option 2: Fix Storyboard subclass setup #

If you really want to use Storyboard:

• Drag a regular UIButton onto your view, then go to the Identity Inspector.
• In the Class field, type GIDSignInButton exactly (capitalization matters!) and select GoogleSignIn from the Module dropdown (if it doesn’t appear, double-check that GoogleSignIn is linked in Build Phases > Link Binary With Libraries).
• If the subclass still won’t stick, close Xcode, delete the derived data folder (you can find it via Xcode > Preferences > Locations > Derived Data), then reopen your project.

Don’t forget AppDelegate setup #

Add this to your AppDelegate.swift to handle the Google Sign-In redirect:

import UIKit
import Firebase
import GoogleSignIn

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        FirebaseApp.configure()
        return true
    }
    
    func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool {
        return GIDSignIn.sharedInstance().handle(url)
    }
}

Final check: Info.plist URL Scheme #

Make sure you’ve added your Google Cloud Console’s REVERSED_CLIENT_ID as a URL Scheme in your Info.plist. You can do this by adding a new row with CFBundleURLTypes, then adding an item with CFBundleURLSchemes containing your reversed client ID.

内容的提问来源于stack exchange，提问作者Dedeepya Reddy