ios - 杀死应用程序后 Facebook AccessToken 为零(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App后，currentAccessToken始终为nil。仅当应用程序仍在后台运行时按下主页按钮并重新打开应用程序时，它才有效。

我开始使用警报，因为在终止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")
    }
}

它总是在警报中显示“1”。

这是一个类似的问题: FBSDKAccessToken currentAccessToken nil after quitting app 或者 iOS 9 Facebook Access Token is nil on future app launches

我已经尝试过:

1. 钥匙串(keychain)不工作
2. 无法通过 Cocoapods 降级到 4.17
3. 更改传输安全性效果不佳

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 token 字符串并在连续启动时重新创建它。

基本上:

1. 获取访问 token 后保存

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

2. 获取访问 token 字符串并在下次启动时重新创建AccessToken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:为简化此示例，将 Facebook 访问 token 字符串保存到 UserDefaults，但理想情况下应将其保存到钥匙串(keychain)。

---

在例子中:

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)
        }
    }
}

(Swift 4/Facebook SDK 4.30)