Pull to Refresh in Swift not Reloading UITableView - ios

Question

I've got JSON filling my UITableView successfully, but the JSON is often updated so I need the ability to refresh. I followed THIS TUTORIAL to implement a pull to refresh control. Visually, it seems like it all works correctly, but when I call tableView.reloadData() the table doesn't reload. However, if I leave the ViewController and return, the table is updated. Why would tableView.reloadData() work in viewDidAppear and viewWillAppear but not in my custom refresh() function?
MainVC.swift file
class MainVC: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet var tableView: UITableView!
var dataArray: NSArray = NSArray()
#IBOutlet var Controller: UISegmentedControl!
var refreshControl:UIRefreshControl!
func refresh(sender:AnyObject)
{
refreshBegin("Refresh",
refreshEnd: {(x:Int) -> () in
self.tableView .reloadData()
println("Table Reloaded")
self.refreshControl.endRefreshing()
})
}
func refreshBegin(newtext:String, refreshEnd:(Int) -> ()) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
println("refreshing")
sleep(2)
dispatch_async(dispatch_get_main_queue()) {
refreshEnd(0)
}
}
}
override func viewWillAppear(animated: Bool) {
self.tableView .reloadData()
}
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.titleView = UIImageView(image: UIImage(named: "logojpg.jpg"))
startConnectionAt("http://www.domain.com/json.php")
refreshControl = UIRefreshControl()
refreshControl.backgroundColor = UIColor.orangeColor()
refreshControl.tintColor = UIColor.whiteColor()
refreshControl.attributedTitle = NSAttributedString(string: "Pull to Refresh")
refreshControl.addTarget(self, action: "refresh:", forControlEvents: UIControlEvents.ValueChanged)
tableView.addSubview(refreshControl)
}
//MARK: JSON Loading
var data: NSMutableData = NSMutableData()
func startConnectionAt(urlPath: String){
var url: NSURL = NSURL(string: urlPath)
var request: NSURLRequest = NSURLRequest(URL: url)
var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: false)
connection.start()
}
func connection(connection: NSURLConnection!, didFailWithError error: NSError!) {
println("Connection failed.\(error.localizedDescription)")
}
func connection(connection: NSURLConnection, didRecieveResponse response: NSURLResponse) {
println("Recieved response")
}
func connection(didReceiveResponse: NSURLConnection!, didReceiveResponse response: NSURLResponse!) {
self.data = NSMutableData()
}
func connection(connection: NSURLConnection!, didReceiveData data: NSData!) {
self.data.appendData(data)
}
func connectionDidFinishLoading(connection: NSURLConnection!) {
var dataAsString: NSString = NSString(data: self.data, encoding: NSUTF8StringEncoding)
var err: NSError
var json: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
var results: NSArray = json["needs"] as NSArray
self.dataArray = results
tableView.reloadData()
println("success")
}
//End loading of JSON
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(tableView: UITableView!, numberOfRowsInSection section: Int) -> Int {
return self.dataArray.count;
}
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
var cell:CustomCell = self.tableView.dequeueReusableCellWithIdentifier("cell") as CustomCell
var rowData: NSDictionary = dataArray[indexPath.row] as NSDictionary
var firstName=rowData["needFirstname"] as String
var descrip=rowData["needDescription"] as String
var poster=rowData["needPoster"] as String
var city=rowData["needCity"] as String
var state=rowData["needState"] as String
var country=rowData["needCountry"] as String
cell.needFirstName.text = firstName
cell.needDescription.text = descrip
cell.needDescription.numberOfLines = 0
cell.needPoster.text = poster
cell.needCity.text = city
cell.needState.text = state
cell.needCountry.text = country
return cell
}
#IBAction func Change(sender: AnyObject) {
if Controller.selectedSegmentIndex == 0 {
startConnectionAt("http://www.domain.com/localJSON.php")
}
else if Controller.selectedSegmentIndex == 1 {
startConnectionAt("http://www.domain.com/intlJSON.php")
}
self.tableView .reloadData()
}
}

Answer 1

Your last comment is right-on in my view.
During your pull to refresh function, you call tableView.reloadData(), however, reloadData() does not inherently do any repopulating the elements in the data source (in your case, dataArray). It simply reloads all the data that's currently in the table view's data source at the time it is called.
So my recommendation would be to construct your refresh function such that the following happens:
Initiate a request to your web service.
When the response comes back (ie, connectionDidFinishLoading is executed), parse the JSON results and assign that result to the dataArray instance. You seem to be doing this already in connectionDidFinishLoading, so it's just a matter of sending the request to your web service, I'd think.
Call tableView.reloadData() to display any new elements that have been added since the last time the tableView's data was displayed. Again, you're doing this already in connectionDidFinishLoading, so #1 is the primary thing that I think needs to happen.

Answer 2

Referring to https://stackoverflow.com/a/25957339
Not sure but maybe the connection is run on a different thread, if so you need to run the table update on the main UI thread
// using Swift's trailing closure syntax:
dispatch_async(dispatch_get_main_queue()) {
self.tableView.reloadData()
}