Deleted row in tableview is reappearing when navigating back - ios

Question

Have friendsviewcontroller in which have uibarbuttonItem to edit friends list and other uibarbuttonitem to create groups for group chatrooms.
Have multiple segue for switching view controllers.
- (void)viewDidLoad
{
[super viewDidLoad];
self.title = #"Groups";
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"New" style:UIBarButtonItemStylePlain target:self
action:#selector(actionNew)];
self.tableView.separatorInset = UIEdgeInsetsZero;
chatrooms = [[NSMutableArray alloc] init];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
if ([PFUser currentUser] != nil)
{
[self refreshTable];
}
else LoginUser(self);
}
#pragma mark - User actions
- (void)actionNew
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Create New Group" message:nil delegate:self
cancelButtonTitle:#"Cancel" otherButtonTitles:#"OK", nil];
alert.alertViewStyle = UIAlertViewStylePlainTextInput;
[alert show];
}
#pragma mark - UIAlertViewDelegate
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex: (NSInteger)buttonIndex=
{
if (buttonIndex != alertView.cancelButtonIndex)
{
UITextField *textField = [alertView textFieldAtIndex:0];
if ([textField.text isEqualToString:#""] == NO)
{
PFObject *object = [PFObject objectWithClassName:PF_CHATROOMS_CLASS_NAME];
object[PF_CHATROOMS_NAME] = textField.text;
[object saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error)
{
if (error == nil)
{
[self refreshTable];
}
else [ProgressHUD showError:#"Network error."];
}];
}
}
}
- (void)refreshTable
{
[ProgressHUD show:nil];
PFQuery *query = [PFQuery queryWithClassName:PF_CHATROOMS_CLASS_NAME];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error)
{
if (error == nil)
{
[chatrooms removeAllObjects];
for (PFObject *object in objects)
{
[chatrooms addObject:object];
}
[ProgressHUD dismiss];
[self.tableView reloadData];
}
else [ProgressHUD showError:#"Network error."];
}];
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [chatrooms count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
if (cell == nil) cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:#"cell"];
PFObject *chatroom = chatrooms[indexPath.row];
cell.textLabel.text = chatroom[PF_CHATROOMS_NAME];
return cell;
}
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
PFObject *chatroom = [chatrooms objectAtIndex:indexPath.row];
[chatrooms removeObjectAtIndex:chatroom];
//[chatrooms removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
}
}
#pragma mark - Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
[tableView deselectRowAtIndexPath:indexPath animated:YES];
PFObject *chatroom = chatrooms[indexPath.row];
NSString *roomId = chatroom.objectId;
CreateMessageItem([PFUser currentUser], roomId, chatroom[PF_CHATROOMS_NAME]);
ChatView *chatView = [[ChatView alloc] initWith:roomId];
chatView.hidesBottomBarWhenPushed = YES;
[self.navigationController pushViewController:chatView animated:YES];
}
Deleted row in table view reappears when navigate back to the TableView
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
PFObject *chatroom = [chatrooms objectAtIndex:indexPath.row];
[chatrooms removeObjectAtIndex:chatroom];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
}
}
Im unable to locate what piece of code i m missing or what exactly i m doing wrong.
If anyone can please point out to that.
Will appreciate so much.
Thanks.

Answer 1

When committing deletion, your code removes objects from chatrooms which is data source of the table view in your case, but this happens in your app's memory, the source from which chatrooms is populated does not change. Thus, speaking in MVC, the app's model state is not updated after the view's state is changed.
Every time the table view is showed up, your code populates chatrooms in refreshTable, if the model's state hasn't been changed, the code gets same list as before, thus the table view doesn't change.
EDIT: Instead of using another approach to refresh the table view, you need to think about what does your app do in this table view. If user can delete stuff in the table view, should your app update model (This model can be a local or remote database, a property list file, etc.) too? If yes, then update model when user inserts or deletes rows in the table view; well, if not, then you are asking a question that is not a problem, or maybe the table view should turn off editing.
EDIT1:
If you do need to update data, based on your code, you may need to do something like this:
- (void)tableView:(UITableView *)tableView
commitEditingStyle:(UITableViewCellEditingStyle)editingStyle
forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
PFObject *chatroom = [chatrooms objectAtIndex:indexPath.row];
[chatrooms removeObjectAtIndex:indexPath.row];
PFQuery *query = [PFQuery queryWithClassName:PF_CHATROOMS_CLASS_NAME];
[query deleteChatroom:chatroom];
[tableView deleteRowsAtIndexPaths:#[indexPath]
withRowAnimation:UITableViewRowAnimationAutomatic];
}
}
That is, you may need to implement method deleteChatroom: of class PFQuery.