How to reload data in a TableView from a different ViewController in Swift

Question

In a ViewController, I'm trying to reload data in a TableView in another ViewController like so:

    (self.presentedViewController as! tableViewController).table.reloadData()

Where tableViewController is the class in the TableView's controller (It's not upper camel case, I know) and table is the TableView. Well, doing this yields "fatal error: unexpectedly found nil while unwrapping an Optional value" and I guess that makes sense since the "presentedViewController" hasn't been loaded yet. I also tried this:

    (self.navigationController!.viewControllers[self.navigationController!.viewControllers.count - 2] as! tableViewController).table.reloadData()

which yielded the same result (I made sure the tableViewController was under the current ViewController on the navigationController stack). I'm baffled about what I should do...I feel like it should be easier to refer to properties in different view controllers. I may be a little vague; if I am, tell me what you need to know!

Answer 1

Xcode 9 • Swift 4

Create a Notification Name:

extension Notification.Name {
    static let reload = Notification.Name("reload")
}

You can post a notification

NotificationCenter.default.post(name: .reload, object: nil)

And add an observer at the view controller that you want to reload the data:

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(reloadTableData), name: .reload, object: nil)
}

@objc func reloadTableData(_ notification: Notification) {
    tableView.reloadData()
}