UITabBarController always open page at the top of UIViewController - swift

Question

I recently implemented into my code a way to scroll to the top of UIViewController by tapping an icon in UITabBar twice. The code is located inside my UITabBarController code. It works great, however the unfortunate side effect I've found is that every time I open up a page on my app, it's now at the top of UIViewController instead of the place where I last left off. I'm sure there's an error somewhere in this code
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) {
pressedCount += 1
if pressedCount > 1 {
scrollToTop()
} else {
//do something for first press
}
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
}
}

Answer 1

Problem is, that when your ViewController disappear, it still has pressedCount property set to 2
So to viewWillAppear add this line to reset this:
pressedCount = 0
also fix if statement in tabBar didSelect item to reset pressedCount every time user presses tabBar item twice
if pressedCount > 1 {
scrollToTop()
pressedCount = 0
} else {
//do something for first press
}