UIBarButtonItem tintColor with UINavigationController - iphone

Question

I have a navigation controller with 2 UIBarButtonItems in my navigation bar. I want to change the tint color only for the one on the right. I have found a way in static to do that:
[[self.navigationController.navigationBar.subviews objectAtIndex:2] setTintColor:[UIColor redColor]];
The problem is when I push a controller into my navigation controller to display another view, when I come back to the root view where my right navigation bar button is supposed to have a custom color, the color of the button is back to its default. And when I click again on it, the app crashes. It says it cannot change the tint color, like if the index for this element in my navigation bar changed.
I have tried other technics found on the internet, but they all failed when I use the navigation controller and come back to the root controller...
Any idea?
Thanks!
Edit 1:
I would like a bordered style button in my UINavigationBar, with a red or green background color.
Regarding the other ways I found, it is pretty much a foreach loop of the views in the navigation bar, and if the view's kind of class is a button item then change the tintColor. It doesn't crash but it applies to all the UIBarButtonItem of my navigation bar (and I just want a specific button, the right one, not all of them). For example this tutorial is half working, my app crashes when coming back to the root view controller.

Answer 1

Digging into the subviews of the navigationcontroller.navigation bar wont fly with Apple, ...
the correct way to change the color of a UIBarButtonItem is to use a customView with the buttonitem. here is a link that explains...
UIBarButtonItem with color?

Answer 2

You simply create a segmented control with just one segment. Set its tint color as you like. You may also want to set its mode to momentary so it optically behaves like a button. Add the segmented control to the bar button item by using the initWithCustomView: initializer. That's how you typically create custom tinted buttons.
Example:
UISegmentedControl *cartControl = [[UISegmentedControl alloc] initWithFrame:CGRectMake(10,7,60,30)];
[cartControl setTintColor:[UIColor colorWithRed:0.35 green:0.47 blue:0.65 alpha:1]];
[cartControl addTarget:self action:#selector(cart:) forControlEvents:UIControlEventValueChanged];
[cartControl setSegmentedControlStyle:UISegmentedControlStyleBar];
[cartControl insertSegmentWithImage:[UIImage imageNamed:#"shopping_cart_white_small.png"] atIndex:0 animated:NO];
[cartControl setMomentary:YES];
UIBarButtonItem *cartButton = [[UIBarButtonItem alloc] initWithCustomView:cartControl];
[cartControl release];
[[self navigationItem] setRightBarButtonItem:cartButton];
[cartButton release];