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I'm trying to make my UITabBarController scroll to the top of the page when pressed twice. I have tried several times to get this to work with no luck. As of now, I only have one class for the UITabBarController on the storyboard that is linked to the code. Am I supposed to link UITabBar as well? Here's my code that I've attempted so far.

 import UIKit

class TabViewController: UITabBarController, UITabBarControllerDelegate 
 var pressedCount: Int = 0


 override func viewDidLoad() 
 super.viewDidLoad()
 self.delegate = self


 // Do any additional setup after loading the view.
 
 @IBAction func unwindToMain(segue: UIStoryboardSegue) 

 override func viewWillAppear(_ animated: Bool) 

 super.viewWillAppear(animated)

 self.navigationController?.isNavigationBarHidden = true
 

 override func didReceiveMemoryWarning() 
 super.didReceiveMemoryWarning()
 // Dispose of any resources that can be recreated.
 
 override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) 
 print("Selected item")
 

 // UITabBarControllerDelegate
 func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) 
 print("Selected view controller")
 
 func tabBarController(_ TabViewController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool 
 guard let viewControllers = viewControllers else return false 
 if viewController == viewControllers[selectedIndex] 
 if let nav = viewController as? UINavigationController 
 guard let topController = nav.viewControllers.last else return true 
 if !topController.isScrolledToTop 
 topController.scrollToTop()
 return false
 else 
 nav.popViewController(animated: true)
 
 return true
 
 

 return true
 



extension UIViewController 
 func scrollToTop() 
 func scrollToTop(view: UIView?) 
 guard let view = view else return 

 switch view 
 case let scrollView as UIScrollView:
 if scrollView.scrollsToTop == true 
 scrollView.setContentOffset(CGPoint(x: 0.0, y: -scrollView.contentInset.top), animated: true)
 return
 
 default:
 break
 

 for subView in view.subviews 
 scrollToTop(view: subView)
 
 

 scrollToTop(view: view)
 

 var isScrolledToTop: Bool 
 if self is UITableViewController 
 return (self as! UITableViewController).tableView.contentOffset.y == 0
 
 for subView in view.subviews 
 if let scrollView = subView as? UIScrollView 
 return (scrollView.contentOffset.y == 0)
 
 
 return true
 

For example:

 var pressedCount: Int = 0

 func tabBar(tabBar: UITabBar, didSelectItem item: UITabBarItem) 

 pressedCount += 1
 if pressedCount > 1 
 scrollToTop(view: self.view)
 else 
 //do something for first press
 
 

Customize the UITabBar and then use the notification time to make the outside world respond!Or record the number of clicks through the UITabBarController agent and then notify the outside world to respond!