Stuck at reassigning TableView Cell property - ios

Question

I'm working on an App where you can track your reading progress for Books.
The HomeViewController contains a TableView that lists the books you have added. It has a progress Bar and shows what page you're on. The AddBookController is for adding Data about a book that gets delegated to the HomeViewController and is then listed as a TableView Row. The BookDetailController is shown when you select a Row and is for updating the Page you're on. I'll provide some screenshots.
I'm stuck at changing the "currentPage" property of the TableView Cell once you update it in the BookDetailViewController. I'm able to send the updatedPage to the HomeViewController (where the TableView is) but I don't know how to align the values of the Cells with the new value. My idea was to use an didSet-observer but I can't figure out how to set it up the right way.
Here is my code:
HomeViewController
class HomeViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, SendingBookDataProtocol {
var updatedPage = String() {
didSet { // probably at the wrong place but everything I've tried didn't work
print(updatedPage)
tableView?.reloadData()
}
}
var items = [BookItem]()
var item: BookItem?
override func viewDidLoad() {
super.viewDidLoad(){
tableView?.delegate = self
tableView?.dataSource = self
let nib = UINib(nibName: "BookCell", bundle: nil)
tableView?.register(nib, forCellReuseIdentifier: "BookCell")
}
func sendDataToHomeController(bookEntry item:BookItem) {
items.append(item)
tableView.reloadData()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
items.count
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let bookDetailVc = self.storyboard?.instantiateViewController(withIdentifier: "BookDetailView") as? BookDetailViewController
let item = items[indexPath.row]
let currentPageInt = Float(item.currentPage)!
let totalPagesInt = Float(item.totalPages)!
let result = Int(totalPagesInt - currentPageInt)
let percentageRead = Int((currentPageInt / totalPagesInt) * 100)
bookDetailVc?.lblName = item.title
bookDetailVc?.lblCurrentPage = Int(Float(item.currentPage)!)
// ...some more Code. Basically just sending the Data to BookDetailViewController
self.navigationController!.pushViewController(bookDetailVc!, animated: true)
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "BookCell", for: indexPath) as! BookCell
item = items[indexPath.row]
cell.title.text = item?.title
//... and so on
cell.pageNumbers.text = "S. " + item!.currentPage + " / " + item!.totalPages //here currentPage needs to be updated
return cell
}
}
BookDetailViewController
class BookDetailViewController: HomeViewController, UIPickerViewDelegate, UIPickerViewDataSource{
#IBOutlet weak var bookTitle: UILabel!
//...
#IBOutlet weak var numberPicker: UIPickerView!
var lblName = String()
//...
var lblCurrentPage = Int()
override func viewDidLoad() {
super.viewDidLoad()
self.numberPicker.delegate = self
self.numberPicker.dataSource = self
//...
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
let valueSelected = pickerData[row] as String
if let homeVc = storyboard?.instantiateViewController(withIdentifier: "getBookData") as? HomeViewController{
homeVc.updatedPage = valueSelected
homeVc.tableView?.reloadData()
}
}
}
AddBookController
protocol SendingBookDataProtocol {
func sendDataToHomeController(bookEntry: BookItem)
}
struct BookItem {
let title,author,currentPage,totalPages:String
let image: UIImage?
}
class AddBookController: UIViewController, UITextFieldDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
var delegate: SendingBookDataProtocol? = nil
#IBAction func buttonSave(_ sender: Any) {
let bookEntry = BookItem(title: textfieldTitle.text!, author: textfieldAuthor.text!, currentPage: fieldCurrentPage.text!, totalPages: fieldTotalPages.text!, image: bookImage)
self.delegate?.sendDataToHomeController(bookEntry: bookEntry)
dismiss(animated: true, completion: nil)
}
}
// rest should be irrelevant
Here are the screenshots:

Answer 1

You have to create a delegate in BookDetailViewController, like this :
protocol BookDetailDelegate: AnyObject {
func updatePage(for bookItem : BookItem)
}
class BookDetailViewController: HomeViewController, UIPickerViewDelegate, UIPickerViewDataSource {
var item: BookItem
var delegate: BookDetailDelegate?
//...
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
let valueSelected = pickerData[row] as String
delegate?.updatePage(valueSelected)
}
}
And then in the HomeViewController:
class HomeViewController {
}
//....
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let bookDetailVc = self.storyboard?.instantiateViewController(withIdentifier: "BookDetailView") as? BookDetailViewController
let item = items[indexPath.row]
bookDetailVc?.item = item
bookDetailVc?.delegate = self
self.navigationController!.pushViewController(bookDetailVc!, animated: true)
}
//.....
extension HomeViewController: BookDetailDelegate {
func updatePage(for bookItem: BookItem) {
let index = item.firstIndex(where: {$0.id = bookItem.id}) //here you should have a UUID or something
item[index] = bookItem
tableView.performBatchUpdates({
self.tableView.reloadRows(at: IndexPath(row: index, section: 0, with: .none)}
}, completion: nil))
}