Displaying an UIViewController that is not present in UITabBarController's controller list - iphone

Question

Let me give an example what about what I want to do:
I have a tab that has 4 TabBarItems, so it contains 4 controllers. And there is a controller that must not get shown up in tab bar's icons, but it will get shown when a button inside one of these 4 controllers are touched. So when it get's shown, the tabbar must not have any selected tabs, every item must be deselected. It must be like a ghost controller that is not shown in tab icons but it's actually a controller that's in tab bar controller.
What's the best way to achieve this? Fyi, I don't want a modal dialog, the tabbar must always be visible underneath.

Answer 1

One thing which might help is knowing when a transition between tabs is happening. If you display your ghost view as soon as the transition happens, you might have enough control to do what you want.
Here's how I do that: first, sub-class UITabBarController to TabViewController (for example). In your TabViewController, include this method:
// Pass this message on to views so they know when transitions are occuring
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController {
UIViewController <UITabBarControllerDelegate> *obj;
for ( obj in self.viewControllers ) {
if ( [obj respondsToSelector:_cmd] ) {
[obj tabBarController:tabBarController didSelectViewController:viewController];
}
}
}
Set each of your tabbed view classes to adopt the UITabBarControllerDelegate protocol. Then, include a method like this in each class to "intercept" the transition events:
// This is called when a transition between tabs happens
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController {
if ( [viewController isEqual:self] ) {
// Transitioning to me
// Do stuff
}
else {
// Transitioning to someone else
// Do stuff
}
}
(note: there might be cleaner ways of implementing this, but it's been working fine for me...)