iOS Swift如何从其他控制器重新加载tableView

Question

I have 2 controllers A and Controller B . Controller A has a TableView and Controller B is a subview that when clicked opens a form and on Submit it enters data into the database. My problem is that I attempt to reload my TableView from Controller B from the user hits submit and I get the following error fatal error: unexpectedly found nil while unwrapping an Optional value from this line

 self.TableSource.reloadData()

Now the data from Controller B is successfully inserted so after I restart my app the data I submit is there . This is my code (TableSource is the TableView outlet)

Controller A

  func reloadTable(latmin: Float,latmax: Float,lonmin: Float, lonmax: Float) {
        let url:URL = URL(string:ConnectionString+"MY-URL")!



        let session = URLSession.shared
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.cachePolicy = NSURLRequest.CachePolicy.reloadIgnoringCacheData
        let parameter = "parameters"
        request.httpBody = parameter.data(using: String.Encoding.utf8)
        session.dataTask(with:request, completionHandler: {(data, response, error) in
            if error != nil {

            } else {
                do {

                    let parsed = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as! [String:Any]



                    if let S = parsedData["myData"] as? [AnyObject]            {


                        for A in Data {
                           // gets Json Data

                                       }

                        DispatchQueue.main.async {
                    // This is what I named my TableView
                            self.TableSource.reloadData()

                        }
                    }

                } catch let error as NSError {
                    print(error)
                }

            }

        }).resume()


    }

That is my HTTP-Request that gets data from the database, now in that same Controller AI have a button that when clicked opens the SubView to Controller B and this is the code

  @IBAction func Post_Action(_ sender: Any) {
        let Popup = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "ControllerB") as! Controller B

        self.addChildViewController(Popup)
        Popup.view.frame = self.view.frame
        self.view.addSubview(Popup.view)
        Popup.didMove(toParentViewController: self)
    }

This is the code in Controller B and this is how I try to reload the TableView in Controller A

@IBAction func Submit_Form(_ sender: Any) {

  // Code that submits the form no issues here


        latmin = 32.18
       latmax = 32.50
       lonmin = -81.12
       lonmax = -81.90

     let Homepage = ControllerA()
       Homepage.reloadTable(latmin: latmin!,latmax: latmax!,lonmin: lonmin!,lonmax: lonmax!)

    }

So as stated before Controller A loads the data from the Database, Controller B has a form and when submitted it enters new data into the database . That whole process works I just now want to update the TableView in Controller A from the form is submitted in Controller B

Answer 1

You can do it with NSNotification

in swift 3.0

Think you have two viwe controllers called viewcontrollerA and viewControllerB

• viewcontrollerA has the tableview.
• you need to reload it from viewcontrolerB

implementaion of viewcontrollerA

create a function to relod your tableview in viewcontrollerA and call it in viewDidLoad

override func viewDidLoad() {
    let notificationNme = NSNotification.Name("NotificationIdf")
    NotificationCenter.default.addObserver(self, selector: #selector(YourControllername.reloadTableview), name: notificationNme, object: nil)
}

func relodaTableview() {
    self.TableSource.reloadData()
}

implementation in viewcontrollerB (where you want to reload tableview)

post the notification in button click or anywhere you want like below

 let notificationNme = NSNotification.Name("NotificationIdf")
 NotificationCenter.default.post(name: notificationNme, object: nil)

hope this will help to you.

Answer 2

I would suggest using protocol:

protocol SomeActionDelegate {
    func didSomeAction()
}

In ViewController B

var delegate: SomeActionDelegate?

In ViewController A when segue

viewControllerB.delegate = self

You should add this

extension ViewControllerA: SomeActionDelegate {
    func didSomeAction() {
         self.tableView.reloadData()
    }
}

And in ViewController B

 func didChangeSomething() {
      self.delegate?.didSomeAction()
 }

It works like when ViewController B didChangeSomething() it sends message to ViewController A that it should didSomeAction()