cellForRowAtIndexPath invocation - ios

Question

I am developing an ToDoList iOS app that uses table view. Cell contents(UITableCellView) are filled by a instance variable of nsmutablearray.
When I add a new ToDoItem, the content is being displayed twice for each row I add. When I put a breakpoint and debug the code I found that cellForRowAtIndexPath method is called twice for every row I add. Why is that happening. How to handle this case or is there any other alternative method to return UITableCellView cell for display.
Method is shown below
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
UITableViewCell *cell;
cell = [self.tableView dequeueReusableCellWithIdentifier:#"ListPrototypeCell" forIndexPath:indexPath];
if (cell == nil) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"ListPrototypeCell"];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
ToDoItem *item = [self.toDoItems objectAtIndex:indexPath.row];
cell.textLabel.text = item.itemName;
return cell;
}
This method is called when user adds new item
-(IBAction)unwindToList:(UIStoryboardSegue *)segue{
AddToDoItemViewController *ITEM = [segue sourceViewController];
ToDoItem *tItem = ITEM.toDoItem;
if (tItem!=nil) {
[self.toDoItems addObject:tItem];
[self.tableView reloadData];
[self setItems:self.toDoItems];
}
}
EDIT:
-(void)setItems:(NSMutableArray *)item{
if (item!=nil) {
tDItems = item;
}
}
tDItems is just another instance variable I am using
Thanks in advance

Answer 1

just check your array if duplicate items are added to the array cause even if cellForRowAtIndexPath is called twice it will not create duplicate cells if items in array are not duplicate. cellForRowAtIndexPath might get called twice because of multiple reloads

Answer 2

i think problem is with the reloading the table data ..try to reload data like this...may be it works
-(IBAction)unwindToList:(UIStoryboardSegue *)segue{
AddToDoItemViewController *ITEM = [segue sourceViewController];
ToDoItem *tItem = ITEM.toDoItem;
if (tItem!=nil) {
[self.toDoItems addObject:tItem];
[self setItems:self.toDoItems];
}
[self.tableView reloadData];
}

Answer 3

Use insertRowsAtIndexPaths with [ToDoItem addObject:[NSIndexPath indexPathForRow:i inSection:0]];
where i= indexPath for where you want to insert Element.
` [tableView beginUpdates];
[insertRowAtIndexArray removeAllObjects];
[insertRowAtIndexArray addObject:[NSIndexPath indexPathForRow:i inSection:0]];
[toDoItems addObject:[NSIndexPath indexPathForRow:i inSection:0]];
i++;
[tableView insertRowsAtIndexPaths:insertRowAtIndexArray withRowAnimation:(UITableViewRowAnimationAutomatic)];
[tableView endUpdates];`

Answer 4

I did a small fix and it worked. Below is the code
-(IBAction)unwindToList:(UIStoryboardSegue *)segue{
AddToDoItemViewController *ITEM = [segue sourceViewController];
ToDoItem *tItem = ITEM.toDoItem;
if (tItem!=nil) {
if ([self.toDoItems count] == 0) { // This is the fix made
[self.toDoItems addObject:tItem];
}
[self.tableView reloadData];
[self setItems:self.toDoItems];
}
}
But I am not sure how the items are getting added from the second item onwards.addObject is working only for the first item and there are no duplicates in the view. But if i remove that if condition then duplicates can be seen. Now I am debugging to see why only it is working for first item.