Swift - 从完成块中解除视图控制器

Question

简单的问题.如果我在一个完成块内 - 例如使用firebase登录facebook ...并且登录成功.如果我想从完成块中解除当前视图控制器(登录视图控制器),我是否需要返回主队列才能执行此操作.我假设登录完成块正在后台线程上完成,并且对UI的任何更改(即解雇当前视图控制器)应该在主线程上完成...这里最好的做法是什么......或者我错过了什么？

@IBAction func facebookLoginTapped(sender: AnyObject) {

    //
    let ref = Firebase(url: "https://XXXX.firebaseio.com")
    let facebookLogin = FBSDKLoginManager()
    facebookLogin.logInWithReadPermissions(["email"], fromViewController: self, handler: { (facebookResult, facebookError) -> Void in
        if facebookError != nil {
            print("Facebook login failed. Error \(facebookError)")
        } else if facebookResult.isCancelled {
            print("Facebook login was cancelled.")
        } else {
            //successfully logged in
            //get facbook access token
            let accessToken = FBSDKAccessToken.currentAccessToken().tokenString
            //use access token to authenticate with firebase
            ref.authWithOAuthProvider("facebook", token: accessToken,
                withCompletionBlock: { error, authData in
                    if error != nil {
                        print("Login failed. \(error)")
                    } else {
                        //authData contains
                        print("Logged in! \(authData)")

                        //pop loginvc back to uservc - DO I NEED TO GET MAIN THREAD HERE BEFORE DISMISSING VIEW CONTROLLER
                        self.dismissViewControllerAnimated(true, completion: nil)
                    }
            })
        }
    })
}

Answer 1

你应该"弹出"回主线程来做到这一点.它非常简单,只需包裹

self.dismissViewControllerAnimated(true, completion: nil) 像这样...

Swift 2.x

dispatch_async(dispatch_get_main_queue()){
    self.dismissViewControllerAnimated(true, completion: nil)
}

Swift 3和Swift 4:

DispatchQueue.main.async {
      self.dismiss(animated: true, completion: nil)
}