如果用户取消登录,Swift ios facebook登录崩溃应用程序

我使用以下代码登录facebook:

@IBAction func fbLoginBtnDidTouch(sender: AnyObject) {
        let fbLoginManager : FBSDKLoginManager = FBSDKLoginManager()
        fbLoginManager.logInWithReadPermissions(["email"], fromViewController: self) { (result, error) -> Void in
            if (error == nil){
                let fbloginresult : FBSDKLoginManagerLoginResult = result
                if(fbloginresult.grantedPermissions.contains("email"))
                {
                    self.getFBUserData()
                }
            }
        }
    }

AppDelegate中:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
  FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)
}

func application(application: UIApplication, openURL url: NSURL, sourceApplication: String?, annotation: AnyObject) -> Bool {
        return FBSDKApplicationDelegate.sharedInstance().application(application, openURL: url, sourceApplication: sourceApplication, annotation: annotation)
    }

这将在webview中启动FB.如果用户从FB帐户接受应用程序,它将按预期返回到应用程序.

但是,如果用户单击否或单击带有FB的webview中的完成按钮,应用程序将崩溃说(致命错误:在解开可选值时意外发现为零)

标记此行:

if(fbloginresult.grantedPermissions.contains("email"))

那么,如果用户点击"否"或"完成",为什么应用程序会崩溃？

首先检查用户是否取消登录.应用程序崩溃,因为没有授予权限.FBSDKLoginManagerLoginResult

if (error == nil){
   let fbloginresult : FBSDKLoginManagerLoginResult = result
   if result.isCancelled {
      return
   }
   if(fbloginresult.grantedPermissions.contains("email"))
     {
         self.getFBUserData()
     }
}