Question

I’m looking at this question and wondering how it was known or where it is documented that [[segmentedControl subviews] objectAtIndex:0] is the currently selected control segment?

That is – how do we know which objectAtIndex number to use?

Answer 1

If you look at other responses, you see that they look for the one that is selected, that is, check what isSelected returns

for (int i = 0; i < [sender.subviews count]; i++) 
{
  if ([[sender.subviews objectAtIndex:i]isSelected]) 
  {               
    ...
  }
}