Refreshing UITableView Asynchronously after Core Data Loaded Swift - ios

Question

I have a UITableView, tViewNews
I have a refresh function which downloads data from my server, stores it into core data, and then the table view loads this data from core data.
It works perfectly
func refresh(refreshControl: UIRefreshControl) {
self.newsArray = [NewsItem]()
self.newslists = [[NewsItem]]()
self.getNewsFromServer()
self.getNewsFromCoreData()
self.tViewNews.reloadData()
refreshControl.endRefreshing()
}
Now, when the user first opens the news viewDidLoad(), I would like for the table view to first load from the core data, then asynchronously populate my table view array from the server (using precisely the same method as the refresh function) and then reload the table view.
So I have tried the following code in my viewDidLoad() function.
override func viewDidLoad() {
super.viewDidLoad()
// Getting news from Core Data
getNewsFromCoreData()
// Updating core data from server and populating table view from core data
dispatch_async(dispatch_get_main_queue()) {
self.newsArray = [NewsItem]()
self.newslists = [[NewsItem]]()
self.getNewsFromServer()
self.getNewsFromCoreData()
self.tViewNews.reloadData()
}
As you can see the functions being run inside the async request are identical to those inside the refresh function.
But!, the refresh function functions properly, populating and reloading the table view. But the async request does absolutely nothing. The table view remains empty. But the functions are running, as tested with print statements.
Anyone know why this is the case?
EDIT - Added extra fucntions
Get Core Data
func getNewsFromCoreData() {
let temp = StaffCoreData()
temp.getAllNews()
newsDates = Dictionary<Int, [NewsItem]>()
for newsobj in temp.newsArray{
if var curdate = newsDates[toNewsItem(newsobj).age]{
curdate.append(toNewsItem(newsobj))
newsDates[toNewsItem(newsobj).age] = curdate
}else{
newsDates[toNewsItem(newsobj).age] = [toNewsItem(newsobj)]
}
}
for var i = 0; i<50; ++i{if let curdate = newsDates[i]{newslists.append(curdate)}}
Get Server Data
runs instance with following method:
func NewsCallReturnsWithSuccess(data: NSData) {
if let jsonObject : AnyObject! = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) {
if let statusesArray = jsonObject as? NSArray{
newsArray.removeAll(keepCapacity: true)
for item in statusesArray {
let datacon : NSData = item.dataUsingEncoding(NSUTF8StringEncoding)!
let jsonObject : NSDictionary! = NSJSONSerialization.JSONObjectWithData(datacon, options: NSJSONReadingOptions.MutableContainers, error: nil) as! NSDictionary
let title : NSString = jsonObject.objectForKey("title") as! NSString
let content : NSString = jsonObject.objectForKey("content") as! NSString
let publishedby : NSString = jsonObject.objectForKey("publishedby") as! NSString
let modified : NSString = jsonObject.objectForKey("modified") as! NSString
let imageurl : NSString = jsonObject.objectForKey("imageurl") as! NSString
let category : NSString = jsonObject.objectForKey("category") as! NSString
let newsItem = NewsItem(title: title as String, content: content as String, category: category as String, imageURL: imageurl as String, publishedBy: publishedby as String, modified: modified as String)
newsArray.append(newsItem)
}
//add complete array to CoreData
let temp = StaffCoreData()
temp.addArrayOfNew(newsArray)
}
}
}

Answer 1

When you are using a different thread for loading your data, you have to return to the main thread when finished loading to update the UI.
Like:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
// load data
dispatch_async(dispatch_get_main_queue()) {
// update ui
}
}
UPDATE
Pls show us your getNewsFromCoreData() and getNewsFromServer() methods and maybe your cellForRowAtIndexPath, too.
override func viewDidLoad() {
super.viewDidLoad()
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
// load data
self.newsArray = [NewsItem]()
self.newslists = [[NewsItem]]()
self.getNewsFromServer()
self.getNewsFromCoreData()
dispatch_async(dispatch_get_main_queue()) {
// update ui
self.tViewNews.reloadData()
}
}
}