UITableView is not updating once the row is deleted - ios

Question

Im working on a project in swift 3.0 and I have two UITableViews where I set data fetched from a core-data module entity called UserIncome. As these data will be populated in two UItableViews in a single UIViewController (filtering based on a String value in the ViewWillAppear delegate method),once a row is been deleted in one UITableView, its array automatically gets updated by the other tableView's objects too. But once I click the back button and come back to the same UIViewController all seems fine. My requirement is to update the UItableView once a row is been deleted so as the core data module. The code as bellow. What am I missing here?
import UIKit
import CoreData
class MyIncomesViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet weak var recurringIncomeTableView: UITableView!
#IBOutlet weak var otherIncomeTableView: UITableView!
//var myIncomeType : String?
var stores = [UserIncome] ()
var other = [UserIncome] ()
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
var rowTbl : Int!
var rowTbl2 : Int!
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewDidAppear(_ animated: Bool) {
stores.removeAll()
other.removeAll()
let request = NSFetchRequest <NSFetchRequestResult> (entityName: "UserIncome")
request.returnsObjectsAsFaults = false
do {
let results = try context.fetch(request) as! [UserIncome]
print("Results from the fetch request are : ", request)
// check data existance
if results.count>0 {
print("results are :", results.count)
for resultGot in results {
//lets check if the data is available and whether the loop is working by printing out the "name"
if let incName = resultGot.incomeName {
print("expence name is :", incName)
//set the value to the global variable as to filter the arrays
let myIncomeType = resultGot.incomeType
if myIncomeType == "Recurring Income"{
stores += [resultGot]
print("my recurring income array is : \(stores)")
}else if myIncomeType == "Other Income"{
other += [resultGot]
print("my other income array is : \(other)")
}
}
}
self.recurringIncomeTableView.reloadData()
self.otherIncomeTableView.reloadData()
}
}catch{
print("No Data to load")
}
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if tableView.tag == 1 {
let cell: RecuringIncomeTableViewCell = tableView.dequeueReusableCell(withIdentifier: "recurringIncomeCell") as! RecuringIncomeTableViewCell
let store = stores [indexPath.row]
cell.incomeNameLabel.text = store.incomeName
cell.amountLabel.text = store.amount
return cell
}
else {
let cell: OtherIncomeTableViewCell = tableView.dequeueReusableCell(withIdentifier: "otherIncomeCell") as! OtherIncomeTableViewCell
let otherIncomes = other [indexPath.row]
cell.incomeNameLabel.text = otherIncomes.incomeName
cell.amountLabel.text = otherIncomes.amount
return cell
}
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
//performSegue(withIdentifier: "editStore", sender: nil)
if tableView.tag == 1 {
rowTbl = tableView.indexPathForSelectedRow?.row
print("current row in tbl 1 is : ",rowTbl)
}else {
rowTbl2 = tableView.indexPathForSelectedRow?.row
print("current row in tbl 2 is : ",rowTbl2)
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "editRecurringIncome"{
let v = segue.destination as! AddIncomeViewController
let indexPath = self.recurringIncomeTableView.indexPathForSelectedRow
let row = indexPath?.row
v.store = stores[row!]
}else if segue.identifier == "editOtherIncome" {
let t = segue.destination as! AddIncomeViewController
let indexPath = self.otherIncomeTableView.indexPathForSelectedRow
let row = indexPath?.row
t.store = other [row!]
}
}
//
func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
print("delete delegate being activated")
return true
}
//For remove row from tableview & object from array.
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
if tableView.tag == 1 {
if editingStyle == .delete {
let task = stores [indexPath.row]
context.delete(task)
(UIApplication.shared.delegate as! AppDelegate).saveContext()
do {
stores = try context.fetch(UserIncome.fetchRequest())
print("Stores deleted from indexPath",stores)
}catch{
print("fail")
}
recurringIncomeTableView.reloadData()
}
self.recurringIncomeTableView.reloadData()
} else if tableView.tag == 2 {
if editingStyle == .delete {
let task = other[indexPath.row]
print("task on otherTblView is : ",task)
context.delete(task)
(UIApplication.shared.delegate as! AppDelegate).saveContext()
otherIncomeTableView.reloadData()
do {
other = try context.fetch(UserIncome.fetchRequest())
print("Stores deleted from indexPath",other)
}catch{
print("fail")
}
}
self.otherIncomeTableView.reloadData()
}
tableView.reloadData()
}
}

Answer 1

you need to delete task like this way
let task = stores [indexPath.row]
context.delete(task)
stores.removeAtIndex(indexPath.row) // i think you forget this line
(UIApplication.shared.delegate as! AppDelegate).saveContext()
try this,hope it will help you

Answer 2

A core data object doesn't really contain any information. It has a pointer to a context and an ID, so when you ask it for information it goes to the store to ask. If the object is deleted from the context then the manage object that you have stored in your array will no longer work and will crash. This is why you should never retain NSManagedObjects. Either
a) Copy the values from core data into an a different object. When you want to delete an object you have to delete it from both the store and the copy that you are retaining. If new objects are inserted, or they are deleted from some other source outside of you viewController it will not update (but also no crash).
b) Use a NSFetchedResultsController and update the results when the values change. This will give a delegate to tell you when changes happen. So all you have to do it delete the object from the store and then the fetchedResultsController will tell you when to remove it.