Question

I have an object data of class EquationData. I also have a custom tableviewcell (balanceCell), which has as a subview a custom text field (balanceCell.leftView). The text field has a property of type NSMutableString equationOrder which changes as the user types in text. I want data to receive notifications as more objects are added to equationOrder.

What I have in the view controller

- (UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {


    equationCell = (EquationCell *) [tableView dequeueReusableCellWithIdentifier:@"equationCell"];

    if (equationCell == nil) {   
        NSArray *nib =   [[NSBundle mainBundle] loadNibNamed:@"EquationCell" owner:self options:nil];
        equationCell = (EquationCell*) [nib objectAtIndex:0];

       [equationCell.leftView addObserver:data forKeyPath:@"equationOrder" options:NSKeyValueObservingOptionNew context:nil];
    }

    return equationCell;
}

What I have in data’s implementation

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
if ([keyPath isEqualToString:@"equationOrder"]) 
NSLog(@"called");

}

However, “called” is not displayed on the screen. I have tried using other variables for data to observe, and I’ve tried changing equationOrder from a property to just a variable.

How do I get data to receive notifications as equationOrder is changed? (I’ve made sure that objects are actually added to equationOrder)

Answer 1

Make sure to use array (or set?) accessors when changing equationOrder. See this question for details.