Swift Tableview checkmark disappeared after relaunch viewcontroller - ios

Question

In my case, I am loading JSON data into tableview. Here, the tableview cell multiple cell selection checkmark and uncheckmark options implemented. If go previous viewcontroller and comeback again tableview controller then last selected checkmark disappeared. How to store it?
JSON Codable
// MARK: - Welcome
struct Root: Codable {
let status: Bool
let data: [Datum]
}
// MARK: - Datum
struct Datum: Codable, Hashable {
let userid, firstname, designation: String?
let profileimage: String?
}
Custom Cell Class
class MyCustomCell: UITableViewCell {
#IBOutlet weak var profileImage: UIImageView!
#IBOutlet weak var nameCellLabel: UILabel!
#IBOutlet weak var subtitleCellLabel: UILabel!
}
Code for Tableview Checkmark
var studentsData = [Datum]()
var sessionData = Set<Datum>()
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell:MyCustomCell = self.tableView.dequeueReusableCell(withIdentifier: cellReuseIdentifier) as! MyCustomCell
let item = self.studentsData[indexPath.row]
cell.nameCellLabel.text = item.firstname
cell.subtitleCellLabel.text = item.designation
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: true)
let item = self.studentsData[indexPath.row]
if let cell = tableView.cellForRow(at: indexPath) {
if cell.accessoryType == .checkmark {
cell.accessoryType = .none
// UnCheckmark cell JSON data Remove from array
self.sessionData.remove(item)
print(sessionData)
} else {
cell.accessoryType = .checkmark
// Checkmark selected data Insert into array
self.sessionData.insert(item)
print(sessionData)
}
}
}

Answer 1

Create a means to store the checkmark status within your data struct
struct Datum: Codable, Hashable {
let userid, firstname, designation: String?
let profileimage: String?
var selected: Bool = false
}
Set the value when you create a cell
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell:MyCustomCell = self.tableView.dequeueReusableCell(withIdentifier: cellReuseIdentifier) as! MyCustomCell
let item = self.studentsData[indexPath.row]
cell.nameCellLabel.text = item.firstname
cell.subtitleCellLabel.text = item.designation
cell.accessoryType = item.selected ? .checkmark : .none
return cell
}
And then in the didSelectRowAt replace the if block with the below to save the change back to the student data and then reset the checkmark accordingly:
self.studentsData[indexPath.row].selected.toggle()
cell.accessoryType = studentsData[indexPath.row].selected ? .checkmark : .none

Answer 2

You should always save the checkMark status in another array or variable.
In case only one item can be selected:
var SELECTED_ITEMS= [YOUR_DATA_TYPE]()//It must be global within tableViewController
in case multiple selection allowed
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: true)
let item = self.studentsData[indexPath.row]
if SELECTED_ITEMS.contain(item){
SELECTED_ITEMS.remove(item)
}else{
SELECTED_ITEMS.append(item)
}
}
Remember SELECTED_ITEM should be Array of your tableviewdata and SELECTED_ITEM is just the same type of your tableview data.
Also if you are initializing your model in ViewDidLoad or ViewWillAppear in tableview controller, make should SELECTED_ITEMS and SELECTED_ITEM are not reset when tableview appears.
then
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
........
cell.accessoryView = SELECTED_ITEMS.contain(item) ? .checkmark:.none// Multi Selection
.........
}
In general, you update your model, a variable or array or whatever fits in your code to keep a track of which indexpath is select/unselected. Then in cellForRowAt you can check the above variable/array... to set accessory.
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath){}
will also work