标签栏单击以滚动到顶部表格视图

Question

I am using this View hierarchy.

UITabBarController > UINavigationController > UITableViewController -> UIViewController (On click of any table cell)

I want to scroll to top of the list on clicking the tab bar item that is currently selected. How can I achieve this? Thanks in advance.

Answer 1

First you need to declare a protocol

protocol RefreshProtocol {
    func scrollToTopRefresh()
}

then what you need to do is to write delegate method of your custom tabBar Controller

  class MainViewController: UITabBarController {}

    extension MainViewController: UITabBarControllerDelegate {
        func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {

            if tabBarController.selectedViewController == viewController {
                if let navController = viewController as? UINavigationController {
                    if let myViewController  = navController.topViewController , let homeController = myViewController as? RefreshProtocol {
                        homeController.scrollToTopRefresh()
                    }
                }
                else {
                   if let homeController = viewController as? RefreshProtocol {
                        homeController.scrollToTopRefresh()
                    }
                }
            }
        } 

Whichever class confirm refresh protocol will implement this function like this

class HomeViewController:UIViewController{}

extension HomeViewController:RefreshProtocol {
    func scrollToTopRefresh () {

                    let indexPath = IndexPath(row: 0, section: 0)
                    self.tableView.scrollToRow(at: indexPath, at: .top, animated: true)
                }
            }
    }

}

Answer 2

Add this to the target of your button

tableView.scrollsToTop = true
tableView.clipsToBounds = true
self.tableView.setContentOffset(CGPoint(x: 0, y: 0), animated: true)