Switch tab bar programmatically in Swift

Thats pretty simple tabBarController is declared as an optional type

var tabBarController: UITabBarController? { get }

The nearest ancestor in the view controller hierarchy that is a tab bar
controller. If the view controller or one of its ancestors is a child
of a tab bar controller, this property contains the owning tab bar
controller. This property is nil if the view controller is not
embedded inside a tab bar controller.

So you just need to add “?” at the end of it:

@IBAction func goToSecond(_ sender: Any) {
    tabBarController?.selectedIndex = 1
}