Question

I have a UITableView with custom UITableViewCells , each of them has a UITextField. I assing to each textField a tag with value : indexPath.row + 100.

Well , i want to update each textField for each cell , when i type something in a specific textField. To be more clear , when I type a number, my viewcontroller should make some calculations and then assing the result to all others textFields, and this must be done each time a modify text from textField , let’s say i typed 1 (make some calculations and assing result to textFields) , then i type 2 , now number to calculate from, will be 12 and so on.

The issue is that i can reloaddata from tableView without closing keyboar. System will automatically hide UIKeyboard , so reloaddata in this case does not work.

I tried to use an NSMutableArray to store all this textFields but they gets a lot , when adding them from cellForRowAtIndexPath.

How can I update properly all these UITextFields ?

Answer 1

It needs to update only visible cells, but not all of them.
Assuming the content calculation formula is pretty simple:

-(NSString*) textForRowAtIndex:(int)rowIndex
{
    return [NSString stringWithFormat:@"%d", startRowValue + rowIndex];
}

And each cell contains UITextField object with tag indexPath.row + 100:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString* cellId = @"cellId";
    UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:cellId];
    if(!cell)
    {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellId] autorelease];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;
        UITextField* tf = [[[UITextField alloc] initWithFrame:CGRectMake(10, 8, 280, 30)] autorelease];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textFieldTextDidChange:) 
                                                     name:UITextFieldTextDidChangeNotification object:tf];
        tf.delegate = (id)self;
        [cell.contentView addSubview:tf];
    }

    UITextField* tf = (UITextField*)[[cell.contentView subviews] lastObject];
    tf.tag = indexPath.row + 100;
    tf.text = [self textForRowAtIndex:indexPath.row];

    return cell;
}

Then all visible cells are to be updated in textFieldTextDidChange: method:

-(void) textFieldTextDidChange:(NSNotification*)notification
{
    UITextField* editedTextField = (UITextField*)[notification object]; 
    int editedRowIndex = editedTextField.tag - 100;
    int editedValue = [editedTextField.text intValue];
    startRowValue = editedValue - editedRowIndex;

    for (NSIndexPath* indexPath in [self.tableView indexPathsForVisibleRows])
    {
        if(indexPath.row != editedRowIndex)
        {
            UITableViewCell* cell = [self.tableView cellForRowAtIndexPath:indexPath];
            UITextField* textField = (UITextField*)[cell.contentView viewWithTag:indexPath.row+100];
            textField.text = [self textForRowAtIndex:indexPath.row];
        }
    }
}

Lets have 50 cells:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 50;
}

And lets hide keyboard when finish editing:

- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [textField resignFirstResponder];
    return YES;
}

Enjoy!