.reloadData() and .setNeedsDisplay() are being ignored - ios

Question

I created a pagination tool from a toolbar that hits this method :
func nextPage(sender: UIBarButtonItem) {
let currentChapter = page.valueForKey("chapter") as! Int
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let fetchRequest = NSFetchRequest(entityName: "Page")
fetchRequest.predicate = NSPredicate(format: "(chapter = %d)", currentChapter + 1)
do {
let result = try managedContext.executeFetchRequest(fetchRequest)
// It is here, I can clearly see we have the old object.
self.page = result[0] as! NSManagedObject
// And here I can clearly see that a new object was set.
self.tableView.reloadData()
self.view.setNeedsDisplay()
} catch {
let fetchError = error as NSError
print(fetchError)
}
}
This method is located in my UIViewController that is set up like so :
import UIKit
import CoreData
class PageViewController: UIViewController, UITableViewDelegate, UINavigationBarDelegate, UITableViewDataSource {
// Mark: Properties
var page: NSManagedObject!
var tableView = UITableView()
var toolBar = UIToolbar()
override func viewDidLoad() {
super.viewDidLoad()
tableView.frame = CGRectMake(0, 0, view.frame.width, view.frame.height - 50)
tableView.estimatedRowHeight = 200
tableView.rowHeight = UITableViewAutomaticDimension
tableView.scrollEnabled = true
tableView.userInteractionEnabled = true
tableView.delegate = self
tableView.dataSource = self
tableView.tableHeaderView = containerView
self.view.addSubview(tableView)
Any ideas why my tableView is not reloading its new data?
Update
As recommended by #Koder and #Simon, I updated my code as so.. but the UI still did not update :
func nextPage(sender: UIBarButtonItem) {
let currentChapter = page.valueForKey("chapter") as! Int
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let fetchRequest = NSFetchRequest(entityName: "Page")
fetchRequest.predicate = NSPredicate(format: "(chapter = %d)", currentChapter + 1)
do {
let result = try managedContext.executeFetchRequest(fetchRequest)
self.page = result[0] as! NSManagedObject
dispatch_async(dispatch_get_main_queue()) {
self.tableView.reloadData()
self.view.setNeedsDisplay()
}
} catch {
let fetchError = error as NSError
print(fetchError)
}
}
Per LucaD's recommendation, I'll also include my numberOfRows and numberOfSections :
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.total
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}

Answer 1

You should fire all the UI refreshing code on the main thread.
For updating tableView, try firing the below from the background thread:
dispatch_async(dispatch_get_main_queue())
{
self.tableView.reloadData()
}
this code block will asynchronously get executed on the main thread.

Answer 2

I suspect you need to move that code into the main thread: UI changes performed in background threads won't update the screen. Try this:
dispatch_async(dispatch_get_main_queue())
{
self.tableView.reloadData()
self.view.setNeedsDisplay()
}
Simon