Added HAX for hiding scope bar while scrolling to allow iOS to collapse the search bar naturally

Author: powerje

SearchController/ViewController.swift

@@ -6,8 +6,10 @@ class ViewController: UITableViewController {
 
     override func viewDidLoad() {
         super.viewDidLoad()
-
+        definesPresentationContext = true
         searchController.searchBar.scopeButtonTitles = ["Scope 1", "Scope 2"]
+        searchController.searchBar.searchBarStyle = .minimal
+        searchController.obscuresBackgroundDuringPresentation = false
         searchController.searchBar.showsScopeBar = true
         navigationItem.searchController = searchController
     }
@@ -22,5 +24,26 @@ class ViewController: UITableViewController {
         return cell
     }
 
-}
+    // HAX: this hides and shows the scope bar appropriately to allow
+    // the system animation of the search bar to complete properly.
+    private var lastContentOffset: CGFloat = 0
+    override func scrollViewDidScroll(_ scrollView: UIScrollView) {
+        let searchBar = searchController.searchBar
+
+        if lastContentOffset > scrollView.contentOffset.y {
+            // Scrolling down, show the scope bar.
+            if !searchBar.showsScopeBar && searchBar.frame.size.height > 44 {
+                searchBar.showsScopeBar = true
+            }
+        } else if lastContentOffset < scrollView.contentOffset.y {
+            // Scrolling up, hide the scope bar to allow the searchBar to collapse
+            // completely.
+            if searchBar.showsScopeBar && searchBar.frame.size.height <= 44 {
+                searchBar.showsScopeBar = false
+            }
+        }
+
+        lastContentOffset = scrollView.contentOffset.y
+    }
 
+}