尝试访问 iOS 应用中的 gmail 收件箱时，Swift 权限被拒绝

如何解决尝试访问 iOS 应用中的 gmail 收件箱时，Swift 权限被拒绝

我有一个可以通过 GIDSignIn 登录的 iOS 应用。该项目最初是通过 Firebase 创建的，因此它还包含 GoogleInfo.plist 信息。

我正在尝试从用户的 Gmail 收件箱中访问邮件，我一直在通过以下示例进行操作：https://www.devfright.com/getting-a-list-of-messages-with-the-gmail-api/

我继续遇到的问题是，我收到 403 错误，指出权限未被拒绝，并且 OATH2 需要一个登录身份验证令牌，该令牌本应从 GIDSignInUser 对象提供。

我的谷歌开发者控制台也启用了 Gmail API

下面是我项目中的代码实现

应用委托

  func application(_ application: UIApplication,didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    FirebaseApp.configure()
    GIDSignIn.sharedInstance().clientID = FirebaseApp.app()?.options.clientID
    //check user sign in
    WebService.shared.silentlySignInUser()
    return true
}

网络服务

 class WebService: NSObject {

static let shared = WebService()
let baseURL = ""
private let scopes = [kGTLRAuthScopeGmailReadonly]
let googleDriveService = GTLRGmailService()
let appDelegate = UIApplication.shared.delegate as! AppDelegate
var googleUser: GIDGoogleUser?

   override init() {
    super.init()

    GIDSignIn.sharedInstance()?.delegate = self
    GIDSignIn.sharedInstance()?.scopes = scopes

}

func silentlySignInUser() {
    
    //safely unwrap optional from gidsignin shared instance
        if let alreadySignedIn = GIDSignIn.sharedInstance()?.hasPrevIoUsSignIn() {
        
        //check if user has already signed in
        if alreadySignedIn {
            //sign in user with prevIoUs credentials
            GIDSignIn.sharedInstance()?.restorePrevIoUsSignIn()
            //load user object in global singleton

            if let loadedUser = GlobalSingleton.shared.load_google_user() {
                
                GlobalSingleton.shared.gUser = loadedUser
               
                //appDelegate.startApplication()
                
            }
        } else {
            print("has not signed in yet")
            
        }
        } else {
            GIDSignIn.sharedInstance()?.signIn()
        }
}
}

  extension WebService: GIDSignInDelegate {
func sign(_ signIn: GIDSignIn!,didSignInFor user: GIDGoogleUser!,withError error: Error!) {
    // A nil error indicates a successful login
    if error == nil {
        // Include authorization headers/values with each Drive API request.
        self.googleUser = user
        loginToFirebase(user)
        
    } else {
        self.googleDriveService.authorizer = nil
        self.googleUser = nil
    }
    // ...
}


    private func loginToFirebase(_ googleUser: GIDGoogleUser) {
        
        guard let authentication = googleUser.authentication else { return }
          
            let credential = GoogleAuthProvider.credential(withIDToken: authentication.idToken,accesstoken: authentication.accesstoken)
            
          
            //sign in to firebase
            Auth.auth().signIn(with: credential) { (authResult,error) in
              if let error = error {
                
                print(error)
                
              } else {
                
                 //user has been successfully signed in to firebase database
                let defaultString = ""
                let user_first_name = googleUser.profile.givenname ?? defaultString
                let user_last_name = googleUser.profile.familyName ?? defaultString
                let user_email = googleUser.profile.email
                
                
                guard user_email != nil else {
                    //show error stating that user email is not a valid google email
                    return
                }
                    let newUserObj = UserObj(first_name: user_first_name,last_name: user_last_name,email: user_email!)
                
                    GlobalSingleton.shared.save_google_user(newUserObj)
                    //if authentication passes then start application
                    self.appDelegate.startApplication()
                
              }
                return
            }
        
    }
    

    func sign(_ signIn: GIDSignIn!,diddisconnectWith user: GIDGoogleUser!,withError error: Error!) {
        // Perform any operations when the user disconnects from app here.
        // ...
    }

func listInBoxMessages() {
    
    let gmailService = GTLRGmailService()
    //authenticated user's email address
    let authorizer = googleUser?.authentication.fetcherAuthorizer()
    self.googleDriveService.authorizer = authorizer
    
    
    let listQuery = GTLRGmailQuery_UsersMessagesList.query(withUserId: "me")
    //populate with all messages that contain "INBox" id
    listQuery.labelIds = ["INBox"]
    
        gmailService.executeQuery(listQuery) { (ticket,response,error) in
            if response != nil {
                print("Response: ")
                print(response)
                
            } else {
                print("Error: ")
                print(error)
                
            }
        }
    
}
}