How to access and refresh a UITableView from another class in Swift

Question

I have a tab bar application and a tab whose view controller is controlled by a UITableView class. I have a class that is used to download data from the server that then sav

Answer 1

You can use protocol or NSNotificationCenter

Example of NSNotificationCenter :

From the UIViewController that downloads the data, you can post a notification after finishing downloading the data and tell other objects that there is new data:

NSNotificationCenter.defaultCenter().
                    postNotificationName("newDataNotif", object: nil)

And any other object that wants to listen to this notification should register to observe (in your case the UITableViewController):

NSNotificationCenter.defaultCenter().
                     addObserver(self, #selector(shouldReload), 
                     name:"newDataNotif", object: nil)

and then you need to implement the method to be called when receive the notification:

func shouldReload() {
  self.tableView.reloadData()
}

Note that the notification can send data also of type [NSObject : AnyObject]? example:

NSNotificationCenter.defaultCenter().
                     postNotificationName("newDataNotif", 
                     object: nil, userInfo: ["data":[dataArray]])

And the observer will be like:

NSNotificationCenter.defaultCenter().
                     addObserver(self, #selector( shouldReload(_:)),
                     name:"newDataNotif", object: nil)

And the method like:

func shouldReload(notification:NSNotification) {
  println(notification.userInfo)
}

and finally in your deinit you should remove observer :

deinit {
    NSNotificationCenter.defaultCenter().removeObserver(self)
}