GIDSignInDelegate协议上的自定义Google登录抛出异常

我正在obj-c中编写一个iOS应用，并使用Google SignIn SDK来执行Google SignIn流程。我想要能够自定义按钮并对其进行一些操作，因此我继续GIDSignInDelegate根据他们的文档来实现自己的协议。但是它会无缘无故地抛出异常。

这是我的视图控制器的最少代码。 viewcontroller.m

    #import "ViewController.h"
    #import <FBSDKLoginKit/FBSDKLoginKit.h>

    @interface ViewController ()


    @property (weak, nonatomic) IBOutlet UIButton *GoogleSignIn;

    @end

    @implementation ViewController

    - (void)viewDidLoad {
        [super viewDidLoad];
        // Do any additional setup after loading the view, typically from a nib.
    }

    - (void)didReceiveMemoryWarning {
        [super didReceiveMemoryWarning];
        // Dispose of any resources that can be recreated.
    }


    - (IBAction)googleButtonTouchUpInside:(id)sender {
        [[GIDSignIn sharedInstance] signIn];
    }

    // Implement these methods only if the GIDSignInUIDelegate is not a subclass of
    // UIViewController.

    // Stop the UIActivityIndicatorView animation that was started when the user
    // pressed the Sign In button
    - (void)signInWillDispatch:(GIDSignIn *)signIn error:(NSError *)error {
        //[UIActivityIndicatorView stopAnimating];
    }

    // Present a view that prompts the user to sign in with Google
    - (void)signIn:(GIDSignIn *)signIn
    presentViewController:(UIViewController *)viewController {
        [self presentViewController:viewController animated:YES completion:nil];
    }

    // Dismiss the "Sign in with Google" view
    - (void)signIn:(GIDSignIn *)signIn
    dismissViewController:(UIViewController *)viewController {
        [self dismissViewControllerAnimated:YES completion:nil];
}

@end

viewcontroller.h

#import <UIKit/UIKit.h>
#import <Google/SignIn.h>

@interface ViewController : UIViewController <GIDSignInUIDelegate>

@end

我确实具有自定义登录流程google doc所需的任何委托方法。我错过了什么吗？