Question

I’m programmatically adding a UISegmentedControl to my UINavigationBar as follows

UISegmentedControl *toggleSwitch = [[UISegmentedControl alloc] initWithItems:[NSArray arrayWithObjects: @"Bar", @"Scatter", nil]];
toggleSwitch.segmentedControlStyle = UISegmentedControlStyleBar;
[toggleSwitch addTarget:self action:@selector(toggleSwitched:) forControlEvents:UIControlEventValueChanged];

UIBarButtonItem *buttonItem = [[UIBarButtonItem alloc] initWithCustomView:toggleSwitch];
self.navigationItem.rightBarButtonItem = buttonItem;
[toggleSwitch release];
[buttonItem release];

I then have a method, toggleSwitched to handle the events:

-(void) toggleSwitched:(id) sender {
    if([sender isKindOfClass:[UISegmentedControl class]]) {
        NSLog(@"%@",((UISegmentedControl*)sender).selectedSegmentIndex );
    }
}

From my reading of the Apple Documentation, this is the proper way to set up the event handling for the touch event.

HOWEVER, when I run the program (in the simulator) and tap the segments, the following things happen:

1. If it’s the first segment (index 0), ‘null’ is logged to the console
2. If it’s the second segment (index 1), the program crashes with EXC_BAD_ACCESS

When I look in the variables window of the debugger, sender is of type UISegmentedControl and the _selectedSegment property appears to be correct (0 or 1).

What am I improperly accessing and how can I set up my delegate function to switch between the two values of the UISegmentedController?

Answer 1

Your NSLog is wrong. selectedSegmentIndex returns NSUInteger, so you need to use @"%d" instead of @"%@". %@ is for objects, so the system is trying to use the number as a memory address that points to a object, and generating an error for you.