How do I pass data from a tab bar controller to one of its tabs?

Question

I have a UITabBarController set up in storyboard. I want to pass a dictionary of data from the tab bar controller for use in the appropriate child tab, which is a standard UIViewController.

This seems like a long questions to answer, but I really don't know where to start. I'm looking for the easiest way through this. Must I make the tabs function programmatically? Pointing me towards any useful developer documentation would also be much appreciated.

-Austin
p.s. i'm new and have so far depended on storyboard for viewcontroller transitions

Answer 1

It took a couple of days, but I discovered a simple solution. In my TabBarController's viewDidLoad method, I can access and set attributes of my the tabbed subviews using

    [[self viewControllers] objectAtIndex:0]

or whatever index you wish to access.

Saving that as an instance of my tab1_viewController gives me a pointer to the object, from which I can get and set my property values. This was initially unclear because storyboard created the tab_viewController objects for me. I never had a chance to initialize them the way I wanted to!

Answer 2

Your best bet is to use notifications.

In your tab bar, you would do this:

NSDictionary *myDictionary; // Populate this with your data.

// Fire the notification along with your NSDictionary object.
[[NSNotificationCenter defaultCenter] postNotificationName:@"Some_Notification_Name" 
                                                    object:myDictionary];        

Then in your child tab ViewController, you would "listen" for that notification.

[[NSNotificationCenter defaultCenter] addObserver:self 
                                         selector:@selector(handleNotification:) 
                                             name:@"Some_Notification_Name" 
                                           object:nil];

- (void)handleNotification:(id)object {
  // Use your NSDictionary object here.
}

Answer 3

If you got an UINavigationController as one of your UITabBarController view controllers, you can do the following:

NSArray *viewControllers = [self.tabBarController viewControllers];
UINavigationController *myNavController = (UINavigationController *)viewControllers[2];
MyViewController *myController = [[myNavController childViewControllers] firstObject];
// Remember to alloc/init objects first if the objects haven't been initialized already.
[myController.whateverArray = [[NSArray alloc] initWithArray:@[@"Example1", @"Example2"]];
[self.tabBarController setSelectedIndex:2];

Answer 4

Using Swift

If you have UINavigationController as one of the tabs in UITabBarController, you want to get the instance of the child view controller instead of creating a new instance and push it to the navigation view controller before changing the tab view index. You can do this...

This sample code assumes the Navigation Controller is at the first tab (index 0) and "childViewController" is embedded in the Navigation Controller.

let viewControllers = self.tabBarController?.viewControllers

let navController = viewControllers![0] as! UINavigationController

let profileViewController = self.storyboard?.instantiateViewControllerWithIdentifier("childViewController") as? ProfileViewController

profileViewController!.parameter1 = "Value1"

profileViewController!.parameter2 = "Value2"

navController.pushViewController(profileViewController!, animated: true)

self.tabBarController?.selectedIndex = 0

Answer 5

With Swift:

if let navController = self.tabBarController?.viewControllers?[1] as? UINavigationController{
        if let testController = navController.childViewControllers.first as? MyViewController{
            testController.data = data
            self.tabBarController?.selectedIndex = 1
        }
}

Answer 6

Got this working...

I have 3 view controller, I have to pass the array from one to another..

Here is what I did

Appending the data to one of Tab View Controller

NSArray *viewControllers = [self.tabBarController viewControllers];
    ListViewController *listView = (ListViewController *)viewControllers[1];
    listView.myArray = self.myArray;
    [self.tabBarController setSelectedIndex:1];

And after that, load the view controller, that's it

UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
ListViewController *listView = (ListViewController *)[storyboard instantiateViewControllerWithIdentifier:@"IDListView"];