State of UIViewController

Question

Hello,

I have a tabbar application, with many views. Is there a way to know if a particular UIViewController is currently visible from within the UIViewController? (looking for a property)

Answer 1

The view's window property is non-nil if a view is currently visible, so check the main view in the view controller:

if (viewController.view.window) {
    // viewController is visible
}

Or if you have a UINavigationController managing the view controllers, you could check its visibleViewController property instead.

Answer 2

You want to use the UITabBarController's selectedViewController property. All view controllers attached to a tab bar controller have a tabBarController property set, so you can, from within any of the view controllers' code:

if([[[self tabBarController] selectedViewController] isEqual:self]){
     //we're in the active controller
}else{
     //we are not
}