Swift: Update Button.setTitle and current UIPageView with NSNotification - ios

Question

Swift 4: I'm using NSNotification post and observe an object between two view controller. My issue is updating the viewController that observes given the received object.
There are two things that needs updating 1. setTitle of a button, 2. the current page on UIPageViewController. How do i update these two things?
I've worked on this the whole day today and yesterday, with no results.
I've tried using struct to do the updating and normal variables.
**YellowViewController - Observes -> Issue here**
let searchedReturnedKey = "Searched"
class YellowViewController: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
let pageView = PageView()
let searched = Notification.Name(rawValue: searchedReturnedKey)
private var isAnimating = false
struct structure {
static var SearchedIndex = Int()
}
override func viewDidLoad() {
super.viewDidLoad()
dataSource = self
delegate = self
setupUIPageView()
setupNavigationBarItem()
createObserver()
}
func createObserver(){
NotificationCenter.default.addObserver(self, selector: #selector(YellowViewController.updateVerseView(notification:)), name: searched, object: nil)
}
#objc func updateVerseView(notification: NSNotification) {
print("Observed")
structure.SearchedIndex = notification.object as! Int
let chapterIndexLabel = doneModel.ChapterIndex
let verseList = doneModel.chapterVerses
let pageView = PageView()
// HERE IS MY ISSUE - booklabel.text and pageview.verses
bookLabel.text = chapterIndexLabel[structure.SearchedIndex]
pageView.verses = verseList[structure.SearchedIndex]
print(structure.SearchedIndex, "Index")
}
func setupUIPageView() {
let verseList = bibleModel.chapterVerses
let chapterIndexLabel = bibleModel.ChapterIndex
let pageViewControllers = [pageView] // Important! UIPageViewController sets ViewController in a list to enable swiping. - Understand this.
pageView.verses = verseList.first! // Important! Setups verses for first view.
bookLabel.text = chapterIndexLabel.first!
setViewControllers(pageViewControllers, direction: .forward, animated: true, completion: nil)
}
var bookLabel = UILabel()
func setupLeftNavItems() {
let bookButton = UIButton(type: .system)
bookButton.setTitle(bookLabel.text! + " 1", for: .normal)
bookButton.setTitleColor(goldColor, for: .normal)
bookButton.titleLabel?.font = UIFont(name: "AvenirNext-DemiBold", size: 18)
bookButton.addTarget(self, action: #selector(handleSearch), for: .touchUpInside)
// bookButton.frame = CGRect(x: 30, y: 0, width: 54, height: 34)
self.navigationItem.leftBarButtonItem = UIBarButtonItem(customView: bookButton)
}
#objc func handleSearch() { // Handles openeing SearchViewController
let searchViewController = SearchViewController()
let navController = UINavigationController(rootViewController: searchViewController)
present(navController, animated: true, completion: nil)
}
func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
isAnimating = true
}
// Handles swiping right - To next chapter.
func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
if isAnimating {
return nil
}
let verseList = bibleModel.chapterVerses
let currentVerseView = (viewController as! PageView).verses
let currentIndex = verseList.index(of: currentVerseView)
let chapterIndexLabel = doneModel.ChapterIndex
if currentIndex! < verseList.count - 1 {
let pageView = PageView()
pageView.verses = verseList[currentIndex! + 1 ]
bookLabel.text = chapterIndexLabel[currentIndex! + 1]
print("Swiped right")
setupLeftNavItems()
createObserver()
return pageView
}
return nil
}
// Handles swiping left - To previous chapter
func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
if isAnimating {
return nil
}
let verseList = bibleModel.chapterVerses
let currentVerseView = (viewController as! PageView).verses
let currentIndex = verseList.index(of: currentVerseView)
let chapterIndexLabel = doneModel.ChapterIndex
if currentIndex! > 0 {
let pageView = PageView()
pageView.verses = verseList[currentIndex! - 1]
bookLabel.text = chapterIndexLabel[currentIndex! - 1]
setupLeftNavItems()
print("Swiped left")
createObserver()
return pageView
}
return nil
}
}
SearchViewController - Post
class SearchViewController: UITableViewController, UISearchBarDelegate {
let cellId = "cellId"
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.titleView = navSearchBar
setupView()
}
func setupView() {
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
tableView.delegate = self
tableView.dataSource = self
navSearchBar.delegate = self
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return Books.count
}
**I post the data from this function**
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let cell = tableView.cellForRow(at: indexPath)
let cellLabelContent = cell!.textLabel!.text
let cellLabelIndex = Books.firstIndex(of: cellLabelContent!)
print("Book name:", cellLabelContent!, "index:", cellLabelIndex!)
let notificationName = Notification.Name(rawValue: searchedReturnedKey)
NotificationCenter.default.post(name: notificationName, object: cellLabelIndex)
dismiss(animated: true, completion: nil)
}
}
Actual result -> No update
Expected result -> Update given object

Answer 1

To be able to update the current view of your UIPageViewController, you would need to do this inside your updateVerseView. The setViewControllers method is correct and efficient method to update a view inside a UIPageViewController.
let pageViewControllers = [pageView]
pageView.verses = verseList[structure.searchedIndex]
setViewControllers(pageViewControllers, direction: .forward, animated: true, completion: nil)
To update your bookLabel.txt you would just need to call your setupLeftNavItems() function.

Answer 2

Here you need toaddObserver with your selector #selector(YellowViewController.updateVerseView(notification:)
I think you set wrong ViewController name