您可以添加自己的按钮，而不是使用谷歌登录按钮

Objective C Version

1) 将自己的按钮添加到故事板中

2) 将操作拖动到viewController中

- (IBAction)googlePlusButtonTouchUpInside:(id)sender {
     [GIDSignIn sharedInstance].delegate = self;
     [GIDSignIn sharedInstance].uiDelegate = self;
     [[GIDSignIn sharedInstance] signIn];
  }

3) 处理委托方法

#pragma mark - Google SignIn Delegate

- (void)signInWillDispatch:(GIDSignIn *)signIn error:(NSError *)error {

  }

//提供一个提示用户登录谷歌的视图

- (void)signIn:(GIDSignIn *)signIn presentViewController:(UIViewController *)viewController
{
    [self presentViewController:viewController animated:YES completion:nil];
}

//取消"使用谷歌登录"视图

- (void)signIn:(GIDSignIn *)signIn dismissViewController:(UIViewController *)viewController {
    [self dismissViewControllerAnimated:YES completion:nil];

}

//已完成登录

- (void)signIn:(GIDSignIn *)signIn didSignInForUser:(GIDGoogleUser *)user
     withError:(NSError *)error {
//user signed in
//get user data in "user" (GIDGoogleUser object)
}

Swift 4 Version

在Swift中，确保你已经添加了briding头，因为库是用objective C编写的

1) 将自己的按钮添加到故事板中

2) 将操作拖动到viewController中

@IBAction func googlePlusButtonTouchUpInside(sender: AnyObject) {
      GIDSignIn.sharedInstance().delegate=self
      GIDSignIn.sharedInstance().uiDelegate=self
      GIDSignIn.sharedInstance().signIn()
} 

3) 处理委托方法

//MARK:Google SignIn Delegate

func signInWillDispatch(_ signIn: GIDSignIn!, error: Error!) {
}

//提供一个提示用户登录谷歌的视图

func signIn(_ signIn: GIDSignIn!,
    presentViewController viewController: UIViewController!) {
  self.present(viewController, animated: true, completion: nil)
}

//取消"使用谷歌登录"视图

func signIn(_ signIn: GIDSignIn!,
    dismissViewController viewController: UIViewController!) {
  self.dismiss(animated: true, completion: nil)
}

//已完成登录

   public func signIn(_ signIn: GIDSignIn!, didSignInForUser user: GIDGoogleUser!,
      withError error: Error!) {
        if (error == nil) {
          // Perform any operations on signed in user here.
          let userId = user.userID                  // For client-side use only!
          let idToken = user.authentication.idToken // Safe to send to the server
          let fullName = user.profile.name
          let givenName = user.profile.givenName
          let familyName = user.profile.familyName
          let email = user.profile.email
          // ...
        } else {
          print("\(error.localized)")
        }
    }

编辑:以下是使用自定义按钮Google Doc reference的参考/证据

在这些示例中，视图控制器是