How do to use the tel:// scheme with stringWithFormat - objective-c

Question

I am trying to create a simple phone book app that allows me to call people from the list. The app lists the names of the contacts and their phone numbers in different sections alphabetically based on the last name. Everything is displaying properly, my issue is when I select a contact and get prompted to "Cancel" or "Call", the "Call" button in the alertView doesn't do anything.
Here is the code I am using (urlString is a global variable):
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog("#didSelectRowAtIndexPath");
NSString *alphabet = [nameIndex objectAtIndex:[indexPath section]];
if([alphabet isEqual:#"A"])
{
UIAlertView *messageAlert = [[UIAlertView alloc] initWithTitle:#"Do you want to call.." message:[SectionA objectAtIndex:indexPath.row] delegate:self cancelButtonTitle:#"Cancel" otherButtonTitles:#"Call", nil];
NSString *urlString = [NSString stringWithFormat:#"tel://%#",[SectionA objectAtIndex:indexPath.row]];
[messageAlert show];
}
[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
There are more if statements with the same code for the different sections of name/numbers, for the sake of space and time I just added the one section.
Here is where I attempt to make the "Call" button actually call the number:
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
if(buttonIndex != [alertView cancelButtonIndex])
{
NSLog(#"Calling phone number");
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:urlString]];
}
}
The alert displays the proper phone number selected, and when I select "Call" nothing happens. But "Calling phone number" does show up in the output log. Stuck at the moment I'm assuming what I store in urlString isn't correct; or how I'm using urlString isn't correct. Any help would be appreciated, thanks!

Answer 1

Change this line
NSString *urlString = [NSString stringWithFormat:#"tel://%#",[SectionA objectAtIndex:indexPath.row]];
to this
urlString = [NSString stringWithFormat:#"tel://%#",[SectionA objectAtIndex:indexPath.row]];
You shadowed a local variable over a global / instance variable, hence the assigned value never reaches the point you expected. In other words, there are two urlString's existing at that point. A local one and one that is scoped globally / instance wide. Your assignment changed the local one, your attempt to use the value uses the global / instance one.