Table scroll when changing tabs - swift

Question

I'm wanting to scroll a table view to the top when someone clicks the tab bar icon.
My tab bar has 4 tabs, the table is on index 0.
I can currently get it to scroll to the top correctly, but I only want it to do it when on index 0, not when returning from the other items.
Currently I have
func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
let tabBarIndex = tabBarController.selectedIndex
if tabBarIndex == 0 {
tableView.scrollToRow(at: IndexPath(row: 0, section: 0), at: .top, animated: true)
}
}
What I want is if you are on index 0, then scroll back to the top, if you are going to 0 from another tab, then leave the scroll as it is.

Answer 1

Edit: It dawned on me you can do the whole process on shouldSelect
You need to know which tab was previously selected. One way to do this is to move the logic to "tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController)"
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
// first condition checks the selected tab is the current view controller
// second verifies you are not coming from another tab
if viewController == self && viewController == tabBarController.selectedViewController {
tableView?.scrollToRow(at: IndexPath(row: 0, section: 0), at: .top, animated: true)
}
return true
}