Question

I have a TabBar in my application and I do this in my AppDelegate:

...
test2ViewController = [[Test1ViewController alloc] init];
...
navigationTest2Controller = [[UINavigationController alloc] initWithRootViewController:test2ViewController];

NSArray *myControllers = [NSArray arrayWithObjects:..., navigationTest2Controller, nil];
[self.myTabBarController setViewControllers:myControllers animated:NO];

Now I have the problem that I am in a ViewController and I want to switch to the “navigationTest2Controller”. I do this in my AppDelegate with:

self.myTabBarController.selectedViewController = navigationTest2Controller;

This works. It switches to this ViewController! This ViewController was already loaded and the viewDidLoad method was called. In this viewDidLoad method is a methos call:

[self myMethod];

I want, that if the view switches to this ViewController this “myMethod” should always be called.
How can I do this? In my AppDelegate before the line

self.myTabBarController.selectedViewController = navigationTest2Controller;

??? Or is there another delegate which will be called every time the ViewController is selected/switched to?

Does anyone know this?

Thanks a lot in advance & Best Regards.

Answer 1

You should place any code that you want to run when the view becomes visible in the -viewWillAppear: or -viewDidAppear method of your view controller.

EDIT: To make this happen only when you switch from a certain view, you can subclass UITabBarController, only modifying the –tabBarController:shouldSelectViewController: method. In that method, you could do something like this:

- (BOOL)tabBarController:(UITabBarController *)tabBarController
shouldSelectViewController:(UIViewController *)viewController
{
    if (self.selectedIndex == 1 &&
        [viewController respondsToSelector:@selector(myMethod)]) {
        [viewController myMethod];
    }

    return YES;
}