Animate the process of tab switching - iphone

Question

Anyone have a walk around on animating the process when switching tabs?
I am currently doing this with 2 issues.
1: It messes up my UIControl colors.
2: It switches the tab first, thereafter perform the animation.
I want to implement something like the effect when pushing a view to navigation stack.
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:1.0];
[UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:bookingVC.view cache:YES];
[UIView commitAnimations];
[self.tabBarController setSelectedIndex:0];
Right now I am doing this, which doesn't have any animation effect.
NSArray *tabBarVC = [self.tabBarController viewControllers];
UINavigationController *firstTabNC = [tabBarVC objectAtIndex:0];
BookingViewController *bookingVC = (BookingViewController *)[[firstTabNC viewControllers] objectAtIndex:0];
[bookingVC setNSStringProperty:newString]; //this string will be displayed on a UITextField whenever viewDidAppear;
// So, I need some animation here when I switch tabs to make it more obvious that the UITextField is updated.
[self.tabBarController setSelectedIndex:0];
I am totally clueless on creating my own animation, please do guide me along. I am opened to ideas to better the presentation.
Thanks.

Answer 1

Any reason you need to use the pre-iOS4 way of animating? Animation blocks simplify this:
[UIView animateWithDuration:1.0
delay:0
options:UIViewAnimationOptionTransitionCurlUp
animations:
^{
// show your desired view however you do it
}
completion:
^(BOOL finished) {
[self.tabBarController setSelectedIndex:0];
}];
EDIT: Sorry, I didn't pick up you were doing a view transition somehow.. silly. There's another block-based method for that case:
[UIView transitionWithView:bookingVC.view
duration:1.0
options:UIViewAnimationOptionsTransitionCurlUp
animations:
^{
// do view transitioning here
}
completion:
^(BOOL finished) {
[self.tabBarController setSelectedIndex:0];
}];
EDIT 2: Alright, so you seem to need some help with the context of all this. You should be animating changes to active tabs in the UITabBarControllerDelegate protocol (which your custom class would implement). In particular, the tabBarController:didSelectViewController: method.
I'd recommend you first override the tabBarController:shouldSelectViewController: method to make sure that you don't accidentally animate a transition from a tab to the same tab:
- (BOOL)tabBarController:(UITabBarController *)tabBarController
shouldSelectViewController:(UIViewController *)viewController
{
return viewController != [tabBarController selectedViewController];
}
In didSelectViewController:, do the animation. I'm also going to take this opportunity to rework your code, because if you're doing it within this method then the selectedIndex of the tab bar controller is handled automatically, and whatever you were doing with bookingVC.view can be replaced by a direct transition between the active tab controller and the new (selected) one:
- (void)tabBarController:(UITabBarController *)tabBarController
didSelectViewController:(UIViewController *)viewController
{
[UIView transitionFromView:[tabBarController selectedViewController].view
toView:viewController.view
duration:1.0
options:UIViewAnimationOptionsTransitionCurlUp |
UIViewAnimationOptionsShowHideTransitionViews
completion:nil];
}
Note here that I use UIViewAnimationOptionsShowHideTransitionViews as part of your animation options. I'm doing this because our animation is on top of the system already changing the active tab, so we don't want to muck it up by trying to remove the view from the view heirarchy at the same time as the system is.

Answer 2

Try placing your animation sequence in didSelectItem::
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item;
Then set up a modalView controller and animate the page curl effect from there.