Question

I have a UITableView which loads through it’s navigationController a new viewcontroller.
This code goes in the tableView:didSelectRowAtIndexPath method:

ConcertDetailViewController *detailVC = [[ConcertDetailViewController alloc] initWithNibName:@"ConcertDetailViewController" bundle:nil];

The UITableView has a model, I want to sent an element of this model to the newly created ViewController.

detailVC.aProd = [_prod objectAtIndex:indexPath.row];

When the value is set I want the detailVC to draw the data on the screen. I thought a custom setter, overwriting the one generated by @synthesize would work.

-(void)setaProd:(NSMutableDictionary *)aProd {
_aProd = aProd;
[self displayAProd];
}

displayAProd just takes the values in aProd and put’s them on the screen, or rather I’m setting some value of an outlet , created in my nib file.

self.prodNameLbl.text = [_aProd objectForKey:@"name"];

Nothing special about this. But it just doesn’t work. I figured out why, I think.
It’s because the setter executes way faster then, loading the whole view into memory.
If I put self.prodNameLbl.text = @”something”; in the viewDidLoad method it does display the correct value in the label.
A quick workaround would be the see if _concerts has been set and from there call displayAProd. Here I’m doubting myself if it’s a good way to load a view. What if the custom setter takes longer to execute the loading the view. The test to see if _concerts has been set will be false and nothing will be displayed. Or is that just impossible to happen ?

Or maybe there’s a better pattern for loading views and passing data to them to be displayed.

Thanks in advanced, Jonas.

Answer 1

The problem is that when you load the view controller from the NIB, the IBOutlets will not be connected to your UILabel and other similar properties during the initWithNibName call.

You need to wait for viewDidLoad to be called on detailVC and call [self displayAProd] from there. At this point, the connections will have been made.

Do a quick test. Put a break point in your didSelectRowAtIndexPath method and, after initialising detailVC, check to see if prodNameLbl is null or not.