ios - Swift - 从完成 block 中解散 View Controller

Question

简单的问题。如果我在完成 block 内 - 例如使用 firebase 的 facebook 登录......并且登录成功。如果我想从完成 block 中关闭当前 View Controller (登录 View Controller )，我是否需要返回主队列来执行此操作。我假设登录完成 block 是在后台线程上完成的，对 UI 的任何更改(即关闭当前 View Controller )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。很简单，就是包起来

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

swift 2.x

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

swift 3 4 和 5:

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