Scroll to the current session instead of just scrolling to the top

Author: zats

trySwift/RootTabBar/RootTabBarController.swift

@@ -20,18 +20,21 @@ class RootTabBarController: UITabBarController, UITabBarControllerDelegate {
         if navigationController.viewControllers.count > 1 {
           navigationController.popViewController(animated: true)
         } else {
-          navigationController.viewControllers.first?.scrollToTop()
+          if let firstController = navigationController.viewControllers.first {
+            if let scrollableToTop = firstController as? ScrollableToTop {
+              scrollableToTop.scrollAfterTabTap()
+            } else {
+              firstController.view.findScrollSubview()?.setContentOffset(.zero, animated: true)
+            }
+          }
         }
       }
     }
   }
 }
 
-private extension UIViewController {
-  func scrollToTop() {
-    let scrollView = view.findScrollSubview()
-    scrollView?.setContentOffset(.zero, animated: true)
-  }
+protocol ScrollableToTop {
+  func scrollAfterTabTap()
 }
 
 private extension UIView {

trySwift/ScheduleViewController.swift

@@ -47,7 +47,6 @@ class ScheduleViewController: ButtonBarPagerTabStripViewController {
 
     override func viewControllers(for pagerTabStripController: PagerTabStripViewController) -> [UIViewController] {
         return days.map { SessionsTableViewController(conferenceDay: $0, scheduleViewController: self) }
-
     }
 
     override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
@@ -59,6 +58,13 @@ class ScheduleViewController: ButtonBarPagerTabStripViewController {
     }
 }
 
+extension ScheduleViewController: ScrollableToTop {
+  func scrollAfterTabTap() {
+    let controller = viewControllers[currentIndex] as! SessionsTableViewController
+    controller.scrollAfterTabTap()
+  }
+}
+
 private extension ScheduleViewController {
 
     @discardableResult

trySwift/SessionsTableViewController.swift

@@ -10,6 +10,7 @@ import UIKit
 import XLPagerTabStrip
 import TrySwiftData
 
+
 class SessionsTableViewController: UITableViewController {
     private lazy var needsToScrollToCurrentSession = Calendar.current.isDateInToday(conferenceDay.date)
 
@@ -33,15 +34,15 @@ class SessionsTableViewController: UITableViewController {
         super.viewDidLoad()
 
         configureTableView()
-        
+
         if traitCollection.forceTouchCapability == .available {
             registerForPreviewing(with: self, sourceView: tableView)
         }
     }
-    
+
     override func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
-    
+
         if needsToScrollToCurrentSession {
             needsToScrollToCurrentSession = false
             scrollToCurrentSession(animated: false)
@@ -55,32 +56,32 @@ class SessionsTableViewController: UITableViewController {
             let isCollapsed = splitViewController?.isCollapsed,
             !isCollapsed,
             !didShowDetail else { return }
-        
+
         didShowDetail = true
         scheduleViewController?.performSegue(withIdentifier: sessionDetailsSegue, sender: firstSelectableSessionVC)
     }
 }
 
 // MARK: - Table view data source
 extension SessionsTableViewController {
-    
+
     override func numberOfSections(in tableView: UITableView) -> Int {
         return conferenceDay.sessionBlocks.count
     }
-    
+
     override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
         return conferenceDay.sessionBlocks[section].sessions.count
     }
-    
+
     override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
         let cell = tableView.dequeueReusableCell(forIndexPath: indexPath) as SessionTableViewCell
-        
+
         let session = conferenceDay.sessionBlocks[indexPath.section].sessions[indexPath.row]
         cell.configure(withSession: session)
-        
+
         return cell
     }
-    
+
     override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
         let session = conferenceDay.sessionBlocks[section]
         let sessionDateFormatter = DateFormatter.sessionDateFormatter
@@ -108,33 +109,33 @@ extension SessionsTableViewController: IndicatorInfoProvider {
 }
 
 extension SessionsTableViewController: UIViewControllerPreviewingDelegate {
-    
+
     func previewingContext(_ previewingContext: UIViewControllerPreviewing, viewControllerForLocation location: CGPoint) -> UIViewController? {
         guard let indexPath = tableView.indexPathForRow(at: location) else { return nil }
         // This will show the cell clearly and blur the rest of the screen for our peek.
         previewingContext.sourceRect = tableView.rectForRow(at: indexPath)
         let session = conferenceDay.sessionBlocks[indexPath.section].sessions[indexPath.row]
         return viewController(for: session)
     }
-    
+
     func previewingContext(_ previewingContext: UIViewControllerPreviewing, commit viewControllerToCommit: UIViewController) {
         scheduleViewController?.performSegue(withIdentifier: sessionDetailsSegue, sender: viewControllerToCommit)
     }
 }
 
 extension SessionsTableViewController {
-    
+
     func configureTableView() {
-        
+
         tableView.register(SessionTableViewCell.self)
-        
+
         tableView.estimatedRowHeight = 160
         tableView.rowHeight = UITableViewAutomaticDimension
     }
 }
 
 private extension SessionsTableViewController {
-    
+
     func viewController(for session: Session) -> UIViewController? {
         switch session.type {
         case .talk, .lightningTalk:
@@ -174,39 +175,39 @@ private extension SessionsTableViewController {
         default:
             return nil
         }
-        
+
         return nil
     }
-    
+
     func sessionDetails(_ presentation: Presentation, session: Session) -> UIViewController {
         let storyboard = UIStoryboard(name: "Main", bundle: nil)
         let sessionDetailsVC = storyboard.instantiateViewController(withIdentifier: String(describing: SessionDetailsViewController.self)) as! SessionDetailsViewController
         sessionDetailsVC.session = session
         sessionDetailsVC.presentation = presentation
         return sessionDetailsVC
     }
-    
+
     func officeHourDetails(_ speaker: Speaker, session: Session) -> UIViewController {
         let officeHoursVC = OfficeHoursDetailViewController()
         officeHoursVC.speaker = speaker
         officeHoursVC.session = session
         return officeHoursVC
     }
-    
+
     func webDisplay(_ event: Event) -> UIViewController {
         let webViewController = WebDisplayViewController()
         webViewController.url = URL(string: event.website!)
         webViewController.displayTitle = event.title
         return webViewController
     }
-    
+
     func webDisplay(_ sponsor: Sponsor) -> UIViewController {
         let webViewController = WebDisplayViewController()
         webViewController.url = URL(string: sponsor.url!)
         webViewController.displayTitle = sponsor.name
         return webViewController
     }
-    
+
     func venueDetails(_ venue: Venue) -> UIViewController {
         let venueDetailsVC = VenueTableViewController(venue: venue)
         venueDetailsVC.tableView.contentInset = UIEdgeInsets(top: 80,left: 0,bottom: 0,right: 0)
@@ -224,15 +225,21 @@ private extension SessionsTableViewController {
 }
 
 extension SessionsTableViewController {
-    
+
     func scrollToCurrentSession(animated: Bool) {
         let secondsFromGMT = TimeZone.current.secondsFromGMT()
         guard
             let date = Date().changed(second: secondsFromGMT),
             let section = conferenceDay.sessionBlocks.index(where: { date < $0.endTime }),
             !conferenceDay.sessionBlocks[section].sessions.isEmpty
             else { return }
-        
+
         tableView.scrollToRow(at: IndexPath(row: 0, section: section), at: .top, animated: animated)
     }
 }
+
+extension SessionsTableViewController: ScrollableToTop {
+  func scrollAfterTabTap() {
+    scrollToCurrentSession(animated: true)
+  }
+}