why does selecting a tabbarController index programatically doesnt call delegate method

Question

when we touch the tabbaritem of the tabbarcontroller the delegate methods are called:

-(BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController;
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController;

but when try to do the same thing programmatically, i.e.

[self.tabbarController setSelectedIndex:selectedIndexNo];

or

[self.tabBarController setSelectedViewController:[self.tabBarController.viewControllers objectAtIndex:0]];

the delegate methods are not called. What is the reason for that?

Answer 1

override UITabBarController setSelectedIndex:

-(void)setSelectedIndex:(NSUInteger)selectedIndex
{
    //must call super function. 
    [super setSelectedIndex:selectedIndex];

    [self myMethod];
}

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{
    [self myMethod];
}