Swift - 从完成块中解除视图控制器

Question

简单的问题。如果我在完成块内 - 例如使用 firebase 的 facebook 登录 ...并且登录成功。如果我想从完成块中关闭当前视图控制器（登录视图控制器），我是否需要返回主队列来执行此操作。我假设登录完成块是在后台线程上完成的，并且对 UI 的任何更改（即关闭当前视图控制器）都应该在主线程上完成......这里的最佳实践是什么......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

您应该“弹出”回主线程来执行此操作。它非常简单，只需包装

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

Swift 2.x

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

Swift 3 4 & 5：

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