Swift 3 UITableView not updating - ios

Question

I was assigned with converting an older Objective C app to Swift.
I had another project come up but when I came back to it and to my somewhat working Swift 2 version, upon updating to Swift 3 the UITableView does not seem to update.
It is built in Interface Builder (IB). The data source and delegate functions are linked in IB.
I made a sample project where I want to reload a different array on a button press. On a button press the main array is set equal to a different array. then self.tableView.reloadData() is called. The array in debugging has a value of 4 and is not empty so numberOfRowsInSection returns a number greater than 0. The table height and width are what you would expect and are visible. The table just does not refresh. The cells populate the first time the array loads.
I have also tried downloading tutorials where they add a new cell to a table but it does not appear to work either. I have also tried manually assigning the app delegate and datasource in MasterViewController.swift. I also tried wrapping the reloadData() call in DispatchQueue.main.async but that did not seem to help either.
Hopefully I'm just missing something very basic here. Below is my MasterViewController file. Thanks for any help.
Current version of Xcode: 8.2.1
Version of swift: 3.0.2
OSX: Sierra 10.12.2
import UIKit
class MasterViewController: UITableViewController {
var detailViewController: DetailViewController? = nil
var objects = [Any]()
var list1 = ["Eggs", "Milk", "Bread", "Bacon"];
var list2 = ["France", "Italy", "England", "Spain"];
var currentArray = [String]();
var setVar = false;
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
self.navigationItem.leftBarButtonItem = self.editButtonItem
if(currentArray.count <= 0){
currentArray = list2;
}else{
currentArray = list1;
}
//self.tableView.dataSource = self;
// self.tableView.delegate = self;
//self.tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell");
//self.tableView.reloadData();
let addButton = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(insertNewObject(_:)))
self.navigationItem.rightBarButtonItem = addButton
if let split = self.splitViewController {
let controllers = split.viewControllers
self.detailViewController = (controllers[controllers.count-1] as! UINavigationController).topViewController as? DetailViewController
}
}
override func viewWillAppear(_ animated: Bool) {
self.clearsSelectionOnViewWillAppear = self.splitViewController!.isCollapsed
super.viewWillAppear(animated)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func insertNewObject(_ sender: Any) {
objects.insert(NSDate(), at: 0)
let indexPath = IndexPath(row: 0, section: 0)
self.tableView.insertRows(at: [indexPath], with: .automatic)
}
// MARK: - Segues
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showDetail" {
if let indexPath = self.tableView.indexPathForSelectedRow {
let object = objects[indexPath.row] as! NSDate
let controller = (segue.destination as! UINavigationController).topViewController as! DetailViewController
controller.detailItem = object
controller.navigationItem.leftBarButtonItem = self.splitViewController?.displayModeButtonItem
controller.navigationItem.leftItemsSupplementBackButton = true
}
}
}
// MARK: - Table View
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return currentArray.count;
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
cell.textLabel!.text = currentArray[indexPath.row];
return cell
}
func refreshUI(){
self.tableView.reloadData();
}
func changeVar(){
if(setVar){
currentArray.removeAll();
self.currentArray = self.list1;
setVar = false;
}else{
currentArray.removeAll();
self.tableView.reloadData();
list2.append("Italy");
self.currentArray = self.list2;
setVar = true;
}
self.refreshUI();
}
override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
// Return false if you do not want the specified item to be editable.
return true
}
override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
objects.remove(at: indexPath.row)
tableView.deleteRows(at: [indexPath], with: .fade)
} else if editingStyle == .insert {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.
}
}
}
class DetailViewController: UIViewController {
#IBOutlet weak var detailDescriptionLabel: UILabel!
#IBOutlet weak var test2: UIButton!
#IBOutlet weak var test1: UIButton!
var mc = MasterViewController();
func configureView() {
// Update the user interface for the detail item.
if let detail = self.detailItem {
if let label = self.detailDescriptionLabel {
label.text = detail.description
}
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
self.configureView()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
var detailItem: NSDate? {
didSet {
// Update the view.
self.configureView()
}
}
#IBAction func button1(){
NSLog("here is the button1");
mc.changeVar();
}
#IBAction func button2(){
NSLog("here is the button2");
mc.changeVar();
}
}

Answer 1

Your tableView is using the data of currentArray in cellForRowAt function.
The only place that you assign to currentArray is in viewDidLoad.
Currently, in the code the add button will cause a new string of the current timestamp to the objects array, As the table is pulling data from currentArray and not objects, it will never change.
I do not see changeVar() function being called anywhere in the code.
Change the target of the add button to call changeVar function and see if that updates the data in the table. If not, you'll have to provide the exact code that your saying is not working, as the current code I wouldn't expect it to change anything.
EDIT:
In your detail view controller you are trying to update a value from the master view controller... But.. It is not the same instance.
var mc = MasterViewController();
^^ This code creates a NEW instance of MasterViewController so calling that code wont change anything on your tableView.
change this line to
weak var mc: MasterViewController?
Then when you create the detailviewcontroller you can do:
let controller = (segue.destination as! UINavigationController).topViewController as! DetailViewController
controller.detailItem = object
controller.mc = self
Then your DetailViewController has a reference to the master controller and can call the function as expected.