iOS Navigation button not working like I expected

[John Baughman]

I have a segmented control with 2 buttons set as the right side button. When I tap either of these buttons the navigation bar slides to the new view and the back button displays correctly, but then immediately slides again as if I were pushing another view on to the stack. For example if I am going from the People view to the Prefernces view, The back button goes like this...

People -> Preferences.

The proper view displays but the didDisplay delegate method does not fire. If I then click the back button which says Preferences, it slides back to a People button and the didDisplay delegate fires. Clicking the People button properly takes me back where I started.

My code looks like this...

   //Code to create the buttons
segmentedControl = [ [ UISegmentedControl alloc ] initWithItems: nil ]; 

segmentedControl.segmentedControlStyle = UISegmentedControlStyleBar; 
[ segmentedControl insertSegmentWithTitle: @"Prefs" atIndex: 0 
				animated: NO ]; 
[ segmentedControl insertSegmentWithTitle: @"Add" atIndex: 1 
				animated: NO ]; 
		
[ segmentedControl addTarget:self 
                        action:@selector(segmentedControlPressed:) 
			forControlEvents:UIControlEventValueChanged ];
		
UIBarButtonItem *segmentItem = [[UIBarButtonItem alloc]
                         initWithCustomView:segmentedControl];
[segmentedControl release];
self.navigationItem.rightBarButtonItem = segmentItem;	
[segmentItem release];

[self.navigationItem setHidesBackButton:YES animated:YES];
self.navigationItem.leftBarButtonItem = self.editButtonItem;

   //code that pushes the view after clicking the prefs button in the segmented control

self.navigationController.navigationBarHidden = NO;
	
PrefsViewController *prefsViewController = [[[PrefsViewController alloc]
        initWithNibName:@"PrefsViewController"	bundle:nil] autorelease];

[self.navigationController pushViewController:prefsViewController
                                        animated:YES];
	
prefsViewController.view.backgroundColor = self.view.backgroundColor;

Not sure where to start in figuring out this one. Maybe someone can point me in the right direction.

Thanks.
John

 

[John Baughman]

Figured it out

I set the target for the sgmentedControl to segmentedControlPressed for value changed events. In segmentedControlPressed I checked to see if selectedSegmentIndex == 0, if 0 called the Prefs action method and else ran the Add action method. This would have worked fine except that I was immediately resetting the selectedSegmentIndex to UISegmentedControlNoSegment which caused segmentedControlPressed method to run again because the segmentedControl selected value changed to -1. Since I was only checking if the selectedSegmentIndex was 0, the Add method was then called, pushing the add view on top of the prefs view. I did not even notice that it was the wrong view showing up.

Fixed it be uniquely checking the value of selectedSegmentIndex. Bad code and good code follows....

    //BAD CODE!!

- (void)segmentedControlPressed:(id)sender
{
	UISegmentedControl *sg = sender;
 
	if (sg.selectedSegmentIndex == 0) { 
		[self prefs]; 

	} else { 		
		[self add];

	} 
	
	sg.selectedSegmentIndex = UISegmentedControlNoSegment;

}

    //GOOD CODE

- (void)segmentedControlPressed:(id)sender
{
	UISegmentedControl *sg = sender;

	if (sg.selectedSegmentIndex == 0) { 
		[self prefs]; 

	} else if(sg.selectedSegmentIndex == 1) { 
		[self add];
	} 
	
	sg.selectedSegmentIndex = UISegmentedControlNoSegment;
}