How to fix `The user canceled the sign-in flow.` with Sign In with Google on iOS?

I also faced the issue before. The GIDSignInButton object don't need addTarget in code or linking @IBAction. The GIDSignInButton class already handle that action for us.

If you are trying to to run GIDSignIn.sharedInstance()?.signIn() in @IBAction. You can run GIDSignIn.sharedInstance()?.presentingViewController = self just before signIn instead of insideviewDidLoad().

@IBAction func googleLogin(_ sender: UIButton) {
    GIDSignIn.sharedInstance()?.presentingViewController = self
    GIDSignIn.sharedInstance()?.signIn()
}