CODEWITHSUNDEEP
iosuiviewcontrollerswift3uitabbarcontroller
Sami
Sami

Reputation: 587

UITabViewController with a UINavigationController as a tab

I have data being shared by two tabs of a UITabBarController. The first tab is in charge of generating and updating the array of data which is consumed by the second tab.

My original method of sharing the data between the tabs worked.

                      ------UIViewController
---UITabBarController
                      ------UIViewController

Using the above method, I accessed the array of data from the first tab as such:

let pointsViewController = self.tabBarController?.viewControllers?.first as! ShowPointsViewController
tableHeaders = pointsViewController.tableHeaders

With ShowPointsViewController being the the first tab

Here is my issue: When I embed my first UIViewController into a UINavigationController and then try to access my array of data using code below, I get a runtime error because the code after the .first... is returning as nil. I understand I am accessing this incorrectly, what is the correct way of achieving the same result?

 let pointsViewController = self.tabBarController?.viewControllers?.first?.navigationController?.topViewController as! ShowPointsViewController

Upvotes: 0

Views: 571

Answers (2)

Adamsor
Adamsor

Reputation: 770

If I understand well you created something like this:

                      ------UINavigationController    ------UIViewController
---UITabBarController
                      ------UINavigationController    ------UIViewController

You are getting nil as self.tabBarController?.viewControllers?.first is already UINavigationController.

Use following code:

 let pointsViewController = (self.tabBarController?.viewControllers?.first as? UINavigationController)?.topViewController as! ShowPointsViewController

Upvotes: 3

shallowThought
shallowThought

Reputation: 19602

self.tabBarController?.viewControllers?.first?is your navigationController, so you are calling .navigationController on the navigationcontroller, which returns nil.

To fix this, remove .navigationController from your call:

let pointsViewController = self.tabBarController?.viewControllers?.first?.topViewController as! ShowPointsViewController

Upvotes: 0

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