Objective-C UITabBarController selecting a tab and calling viewDidAppear

self.tabBarController.selectedIndex = 3;
[self.tabBarController.selectedViewController viewDidAppear:YES];

if inside a custom tabbarcontroller doing this

//call viewWillDisappear in the current view
[self.selectedViewController viewWillDisappear:YES];

//change view
self.selectedIndex = tabID;

//call viewDidAppear in the current view
[self.selectedViewController viewDidAppear:YES];