杀死应用程序后 Facebook AccessToken nil (iOS)

Question

我正在开发一个使用FacebookSDK登录的 iOS 应用程序。

登录并杀死应用程序后，currentAccessToken始终为零。它仅在我按下主页按钮并在应用程序仍在后台运行时重新打开它时才有效。

我开始使用警报，因为在杀死应用程序后日志无法正常工作。

AppDelegate.swift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

    FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)

    let accessToken = FBSDKAccessToken.current()
    if accessToken == nil {
        Auth.auth().addStateDidChangeListener { (auth, user) in
            alert(title: user?.uid ?? "1")
        }
        alert(title: "2")
    } else {
        alert(title: accessToken?.userID ?? "3")
    }
}

它始终在警报中显示“1”。

这是一个类似的问题： 退出应用程序后 FBSDKAccessToken currentAccessToken nil 或 iOS 9 Facebook Access Token 在未来的应用程序启动时为零

我已经尝试过：

1. 钥匙扣不工作
2. 无法通过 Cocoapods 降级到 4.17
3. 更改传输安全性不起作用

帮助/建议，

提前致谢。

Answer 1

AccessToken.current不会持续存在，因此您必须手动保存访问令牌字符串并在连续启动时重新创建它。

基本上：

1. 获得访问令牌后保存

   let strAuthenticationToken = accessToken.authenticationToken
   UserDefaults.standard.set(strAuthenticationToken,
                         forKey: "AccessToken_Facebook")
   

2. 获取访问令牌字符串并AccessToken在下次启动时重新创建对象

   if let strAuthenticationToken = UserDefaults.standard.string(forKey: "AccessToken_Facebook") {
   //Create AccessToken for facebook login
   let accessToken = AccessToken(authenticationToken: strAuthenticationToken)
   
   //...Skip Login and directly proceed to get facebook profile data with the AccessToken
   }
   

注意：为了便于此示例，Facebook 访问令牌字符串将被保存到，UserDefaults但理想情况下应保存到钥匙串。

在示例中：

func loginWithFacebook() {
    //Check for previous Access Token
    if let accessToken  = AccessToken.current {
        //AccessToken was obtained during same session
        getAccountDetails(withAccessToken: accessToken)
    }
    else if let strAuthenticationToken = UserDefaults.standard.string(forKey: "AccessToken_Facebook") {
        //A previous access token string was saved so create the required AccessToken object
        let accessToken = AccessToken(authenticationToken: strAuthenticationToken)

        //Skip Login and directly proceed to get facebook profile data with an AccessToken
        getAccountDetails(withAccessToken: accessToken)
    }
    else {
        //Access Token was not available so do the normal login flow to obtain the Access Token
        doFacebookLogin()
    }
}

func doFacebookLogin() {
    LoginManager().logIn(readPermissions: [.publicProfile, .email], viewController: nil) { loginResult in
        switch loginResult {
        case .failed(let error):
            print(error)

        case .cancelled:
            print("User cancelled login.")

        case .success(let grantedPermissions,
                      let declinedPermissions,
                      let accessToken):

            //Save Access Token string for silent login purpose later
            let strAuthenticationToken = accessToken.authenticationToken
            UserDefaults.standard.set(strAuthenticationToken,
                                      forKey: "AccessToken_Facebook")

            //Proceed to get facebook profile data
            self.getAccountDetails(withAccessToken: accessToken)
        }
    }
}

func getAccountDetails(withAccessToken accessToken: AccessToken) {
    let graphRequest: GraphRequest = GraphRequest(graphPath     : "me",
                                                  parameters    : ["fields" : "id, name, email"],
                                                  accessToken   : accessToken,
                                                  httpMethod    : GraphRequestHTTPMethod.GET,
                                                  apiVersion    : GraphAPIVersion.defaultVersion)
    graphRequest.start { (response, result) in
        switch result {
        case .success(let resultResponse):
            print(resultResponse)
        case .failed(let error):
            print(error)
        }
    }
}

（斯威夫特 4 / Facebook SDK 4.30）