Tableview using realm won't reload when deleted in swift - ios

Question

I have a simple tableView with saved data. I created a delete button that lets me multi-delete from realm. That part works, it is when the tableview is suppose to reload that it seems to not work. I have seen a lot of answers that say you should reload it on the main thread, or view or whatever, using dispatchQueue.main.async
using just normal tableView.reloadData() didn't reload the tableview but when I use the dispatchQueue version it does delete a value but usually the last value in the tableView.
For example my tableView has the strings Uno and Un in that descending order. If I chose to delete Uno when I press the delete button the tableview does reload leaving only one value but that value is Uno, but realm Database tells me I deleted Uno and when I go back to that view it shows Un. It just isn't reloading correctly.
I have tried to place the reloadData in the dispatch at many different locations, but it still doesn't reload correctly. I am curious what I am doing wrong.
this is the viewController with the tableview where I delete the data in the tableView:
import UIKit
import Realm
import RealmSwift
class OtherViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet weak var otherTableView: UITableView!
var realm: Realm!
var realmedData = ""
var realmList: Results<Realmed> {
get {
return realm.objects(Realmed.self)
}
}
let deleteBtn = UIBarButtonItem()
var testingBool = false
var realmArr = [String]()
var idValue = [Int]()
var idArr = [Int]()
var spanArrValue: [String] = []
override func viewDidLoad() {
super.viewDidLoad()
otherTableView.reloadData()
realm = try! Realm()
self.otherTableView.delegate = self
self.otherTableView.dataSource = self
self.otherTableView.reloadData()
deleteBtnInfo(btn: deleteBtn)
self.navigationItem.rightBarButtonItem = deleteBtn
}
func deleteBtnInfo(btn: UIBarButtonItem) {
btn.title = "Delete"
btn.style = .plain
btn.target = self
btn.action = #selector(didTapDeleteBtn(sender:))
testingBool = false
}
#objc func didTapDeleteBtn(sender: AnyObject) {
testingBool = !testingBool
if testingBool == true {
deleteBtn.title = "Remove"
otherTableView.allowsMultipleSelection = true
otherTableView.allowsMultipleSelectionDuringEditing = true
} else if testingBool == false {
deleteBtn.title = "Delete"
didPressRemove()
DispatchQueue.main.async {
self.otherTableView.reloadData()
}
otherTableView.allowsMultipleSelection = false
otherTableView.allowsMultipleSelectionDuringEditing = false
}
}
func didPressRemove() {
if idValue.count == 0 {
print("Please Select what to Delete")
} else {
deleteRealm(idInt: idValue)
}
}
func deleteRealm(idInt: [Int]) {
do {
try realm.write {
for deleteIndex in idInt {
let deleteValue = realm.objects(RealmTwo.self).filter("id == %#", deleteIndex as Any)
print(deleteIndex)
realm.delete(deleteValue)
}
}
} catch {
}
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
var counted = realm.objects(RealmTwo.self).filter("realmLbl == %#", realmedData)
return counted.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "otherCell", for: indexPath) as! OtherTableViewCell
var celledItem = realm.objects(Realmed.self)
for item in celledItem {
for items in item.realmTwo {
self.idArr.append(items.id)
self.realmArr.append(items.spanish)
}
}
cell.otherLbl.text = "\(realmArr[indexPath.row])"
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
if testingBool == false {
print(realmArr[indexPath.row])
} else {
self.idValue.append(idArr[indexPath.row])
print(spanArrValue)
}
}
func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
if testingBool == true {
if let index = idValue.index(of: idArr[indexPath.row]) {
idValue.remove(at: index)
print(spanArrValue)
}
}
}
}
this is the realm class for the data that I am trying to delete.
import Foundation
import UIKit
import Realm
import RealmSwift
class RealmTwo: Object {
#objc dynamic var id = Int()
#objc dynamic var realmLbl = String()
#objc dynamic var spanish = String()
#objc dynamic var french = String()
let realmed = LinkingObjects(fromType: Realmed.self, property: "realmTwo")
convenience init(id: Int, realmLbl: String, spanish: String, french: String) {
self.init()
self.id = id
self.realmLbl = realmLbl
self.spanish = spanish
self.french = french
}
}
As I said above, I placed reloadData() in different places and these are where I placed them, just in case you want to know:
func didPressRemove() {
if idValue.count == 0 {
print("Please Select what to Delete")
} else {
deleteRealm(idInt: idValue)
DispatchQueue.main.async {
self.otherTableView.reloadData()
}
}
}
func deleteRealm(idInt: [Int]) {
do {
try realm.write {
for deleteIndex in idInt {
let deleteValue = realm.objects(RealmTwo.self).filter("id == %#", deleteIndex as Any)
print(deleteIndex)
realm.delete(deleteValue)
DispatchQueue.main.async {
self.otherTableView.reloadData()
}
}
}
} catch {
}
}
I am just not sure where the reloadData is suppose to go, or if that is the real problem. Thank you for the help, and ask if there is anything else I can do.

Answer 1

There are a couple of issues but the main issue is that you're deleting the object from realm but that object is still hanging around in your dataSource tableView array, realmArr.
There are a whole bunch of solutions but the simplest is to add an observer to the realm results and when an item is added, changed or removed, have that update your dataSource array and then reload the tableview. One option also here is to use those results as the dataSource instead of a separate array. Realm Results objects behave very similar to an array and are great a a dataSource.
Conceptually the realm code is similar to
notificationToken = results.observe { [weak self] (changes: RealmCollectionChange) in
guard let tableView = self?.tableView else { return }
switch changes {
case .initial:
tableView.reloadData() //this is when the realm data is intially loaded.
case .update(_, let deletions, let insertions, let modifications):
//handle add, edit and modify per event.
// with an add, add the provided object to your dataSource
// same thing for remove and modify
case .error(let error):
// An error occurred while opening the Realm file on the background worker thread
fatalError("\(error)")
}
//reload the tableView now the dataSource has been updated
}
There are several options of handling those events and they are all covered in the Realm documentation. See Realm Notifications for further details about setting up the notifications.
A second option is to manually keep things in sync; e.g. when deleting the item from Realm, also delete the item from your dataSource array

Answer 2

This is how I managed to solve this problem.
import UIKit
import Realm
import RealmSwift
class OtherViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
var notificationToken: NotificationToken? = nil
#IBOutlet weak var otherTableView: UITableView!
var realm: Realm!
var realmedData = ""
var realmList: Results<RealmTwo> {
get {
return realm.objects(RealmTwo.self).filter("%# == realmLbl", realmedData)
}
}
var realmingList: Results<RealmTwo> {
get {
return realm.objects(RealmTwo.self)
}
}
let deleteBtn = UIBarButtonItem()
var testingBool = false
var realmArr = [String]()
var idValue = [Int]()
var idArr = [Int]()
var spanArrValue: [String] = []
override func viewDidLoad() {
super.viewDidLoad()
otherTableView.allowsMultipleSelectionDuringEditing = true
realm = try! Realm()
notificationToken = realmList.observe { [weak self] (changes: RealmCollectionChange) in
guard let tableView = self?.otherTableView else {return}
switch changes {
case .initial:
tableView.reloadData()
case .update(_, let deletions, let insertions, let modifications):
tableView.beginUpdates()
tableView.insertRows(at: insertions.map({ IndexPath(row: $0, section: 0) }),
with: .automatic)
tableView.deleteRows(at: deletions.map({ IndexPath(row: $0, section: 0)}),
with: .automatic)
tableView.reloadRows(at: modifications.map({ IndexPath(row: $0, section: 0) }),
with: .automatic)
tableView.endUpdates()
case .error(let error):
fatalError("\(error)")
}
}
self.otherTableView.delegate = self
self.otherTableView.dataSource = self
self.otherTableView.reloadData()
deleteBtnInfo(btn: deleteBtn)
self.navigationItem.rightBarButtonItem = deleteBtn
}
func deleteBtnInfo(btn: UIBarButtonItem) {
btn.title = "Delete"
btn.style = .plain
btn.target = self
btn.action = #selector(didTapDeleteBtn(sender:))
testingBool = false
}
#objc func didTapDeleteBtn(sender: AnyObject) {
testingBool = !testingBool
if testingBool == true {
deleteBtn.title = "Remove"
} else if testingBool == false {
deleteBtn.title = "Delete"
}
}
func didPressRemove() {
if testingBool == false {
print("Select what to Delete")
} else {
deleteRealm(idInt: idValue)
otherTableView.isEditing = false
}
}
#IBAction func pressEdit(_ sender: Any) {
testingBool = !testingBool
if testingBool == true {
otherTableView.isEditing = true
} else if testingBool == false {
otherTableView.isEditing = false
}
}
#IBAction func pressDelete(_ sender: Any) {
deleteRealm(idInt: idValue)
}
func deleteRealm(idInt: [Int]) {
do {
try realm.write {
for deleteIndex in idInt {
let deletingValue = realmList.filter("id == %#", deleteIndex as Any)
print("DeleteValue: \(deletingValue)")
realm.delete(deletingValue)
}
}
} catch {
}
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return realmList.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "otherCell", for: indexPath) as! OtherTableViewCell
cell.otherLbl.text = realmList.filter("%# == realmLbl", realmedData)[indexPath.row].spanish
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
if otherTableView.isEditing == false {
} else {
let idArr = realmList.filter("%# == realmLbl", realmedData)[indexPath.row].id
self.idValue.append(idArr)
print("ID: \(idValue)")
}
}
func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
if otherTableView.isEditing == true {
let idArr = realmList.filter("%# == realmLbl", realmedData)[indexPath.row].id
if let index = idValue.index(of: idArr) {
idValue.remove(at: index)
print("ID: \(idValue)")
}
}
}
deinit {
notificationToken?.invalidate()
}
}
Thank you