iOS – Showing a view controller already in the navigation stack - ios

Question

This is probably easily sorted but I can't figure it out. I have a tab bar application with two tabs, each tab has a UINavigationController.
Let's say that I in tab 1 push a viewcontroller called ItemViewController, then I go to tab 2. From tab 2 I want to programatically display the ItemViewController. So it should first take me to tab 1 and then display the ItemViewController.
This is easily achievable by just tapping on the tab 1 tab item but I want to do this programtically for other reasons.
What I'm doing right now to achieve this:
[tab1NavController popToRootViewControllerAnimated:NO];
[tabBarController setSelectedIndex:0];
[tab1NavController pushViewController:itemViewController animated:NO];
I would like to be able to do something like this in pseudo-code:
if(viewControllerIWantToDisplayIsOnNavStack)
[tab1NavController presentViewController:viewControllerIWantToDisplay];
else
//instantiate and pushviewcontroller onto stack
How can I achieve this?

Answer 1

// check if the desired controller is on the stack in tab 1
if([[tab1NavController viewControllers] containsObject:viewControllerIWantToDisplay]) {
// desired controller is on the stack, let's see if it's on top
if(tab1NavController.topViewController == viewControllerIWantToDisplay) {
// no need to do anything
}
else {
// we need to pop to the desired view controller
[tab1NavController popToViewController:viewControllerIWantToDisplay animated:NO];
}
} else {
// desired controller not on the stack
[tab1NavController pushViewController:viewControllerIWantToDisplay animated:NO];
}
So you don't have to pop to root view controller in the tab 1 any more.

Answer 2

for me following way worked, i used loop to check if class is in stack array
NSInteger viewControllersCount = 0;
UIViewController *rootViewController = nil;
Yourcontroller *viewController = nil;
NSArray *viewControllers = self.navigationController.viewControllers;
viewControllersCount = viewControllers.count - 1;
for (int i = viewControllersCount ; i > 0 ; i--) {
rootViewController = [viewControllers objectAtIndex:i];
if([rootViewController isKindOfClass:[Yourcontroller class]])
{
viewController = (NWAAccountViewC *)rootViewController;
[self.navigationController popToViewController:rootViewController animated:YES];
break;
}
}

Answer 3

it's very easy to programmatically select another tab, just do this:
tabbarcontroller.selectedIndex = tabNr;
But I see you already know this. You can check whether the top view controller on the stack is the type of viewcontroller you need by checking like this:
if([navigationcontroller.topviewcontroller isKindOfClass:[Yourcontroller class]])
{
//change tabbar or something else
}