Swift - when is data actually loaded in TableViewController - swift

Question

I'm very much a Swift beginner - am populating a table view from Firebase data.
In the table footer I want to display some calculated totals under the table columns. However when calling footerCell.configure(priceLines, isPortrait: isPortrait) the priceLines dictionary is still empty.
How to remedy this?
Thanks in advance, André Hartman, Belgium
import UIKit
import FirebaseDatabase
class ListTableViewController: UITableViewController {
var priceLines = [NSDictionary]()
var isPortrait = false
override func viewDidLoad() {
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ListTableViewController.rotated), name: UIDeviceOrientationDidChangeNotification, object: nil)
loadDataFromFirebase()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return priceLines.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("profileCell", forIndexPath: indexPath) as! PriceTableViewCell
cell.configure(priceLines, row: indexPath.row, isPortrait: isPortrait, source: "intraday")
return cell
}
override func tableView(tableView: UITableView,viewForHeaderInSection section: Int) -> UIView? {
let headerCell = tableView.dequeueReusableCellWithIdentifier("HeaderCell") as! CustomHeaderCell
headerCell.configure(isPortrait)
return headerCell
}
override func tableView(tableView: UITableView, viewForFooterInSection section: Int) -> UIView? {
let footerCell = tableView.dequeueReusableCellWithIdentifier("FooterCell") as! CustomFooterCell
footerCell.configure(priceLines, isPortrait: isPortrait)
return footerCell
}
override func tableView(tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
return 30.0
}
override func tableView (tableView:UITableView, heightForHeaderInSection section:Int) -> CGFloat
{
return 50.0;
}
// MARK:- Load data from Firebase
func loadDataFromFirebase() {
UIApplication.sharedApplication().networkActivityIndicatorVisible = true
refInter.observeEventType(.Value, withBlock: { snapshot in
var tempItems = [NSDictionary]()
for item in snapshot.children {
let child = item as! FIRDataSnapshot
let dict = child.value as! NSDictionary
tempItems.append(dict)
}
self.priceLines = tempItems
self.tableView.reloadData()
UIApplication.sharedApplication().networkActivityIndicatorVisible = false
})
}
func rotated()
{
let newDisplay = (UIDeviceOrientationIsLandscape(UIDevice.currentDevice().orientation))
if(newDisplay != isPortrait){
self.tableView.reloadData()
}
isPortrait = newDisplay
}
}

Answer 1

The documentation clearly says that
When the table view is about to appear the first time it’s loaded, the
table-view controller reloads the table view’s data.
So, it will reload the table automatically somewhere between viewDidLoad and viewWillAppear. Your priceLines is empty at this point and will be populated with data only when the closure in the method loadDataFromFirebase is fired. I'm not sure when it happens in your case, but as you call implicitly reloadData then you should have already priceLines nonempty (of course if the results in the closure have some data)