Rudimentary autocomplete focus

App/Autocomplete/AutocompleteViewController.swift

@@ -29,6 +29,8 @@ class AutocompleteViewController: UIViewController, UICollectionViewDelegate
         case HistoryItems
     }
     
+    override var canBecomeFirstResponder: Bool { true }
+    
     public let collectionView: UICollectionView
     
     private let autocompleteView: AutocompleteView

App/Browser View/BrowserViewController.swift

@@ -54,6 +54,8 @@ class BrowserViewController: UIViewController
     
     override var preferredStatusBarStyle: UIStatusBarStyle { .lightContent }
     
+    internal var changingFocusToAutocompleteController = false
+    
     init() {
         self.tab = tabController.tabs.first!
         self.tabBarViewController = TabBarViewController(tabController: tabController)
@@ -198,6 +200,7 @@ class BrowserViewController: UIViewController
         }), for: .touchUpInside)
         
         // TextField delegate
+        toolbarController.urlBar.delegate = self
         toolbarController.urlBar.textField.delegate = self
         
         // Autocomplete controller
@@ -551,7 +554,9 @@ extension BrowserViewController: UITextFieldDelegate
     }
     
     func textFieldDidEndEditing(_ textField: UITextField) {
-        autocompleteViewController.view.isHidden = true
+        if !changingFocusToAutocompleteController {
+            autocompleteViewController.view.isHidden = true
+        }
     }
 }
 
@@ -561,3 +566,12 @@ extension BrowserViewController: ReaderViewControllerDelegate
         tab.beginLoadingURL(navigationURL)
     }
 }
+
+extension BrowserViewController: URLBarDelegate
+{
+    func urlBarRequestedFocusEscape(_ urlBar: URLBar) {
+        changingFocusToAutocompleteController = true
+            _ = self.autocompleteViewController.becomeFirstResponder()
+        changingFocusToAutocompleteController = false
+    }
+}

App/Titlebar and URL Bar/URLBar.swift

@@ -7,13 +7,29 @@
 
 import UIKit
 
+protocol URLBarDelegate: AnyObject
+{
+    func urlBarRequestedFocusEscape(_ urlBar: URLBar)
+}
+
+class TextFieldWithKeyCommands: UITextField
+{
+    internal var _keyCommands: [UIKeyCommand]? = []
+    override var keyCommands: [UIKeyCommand]? {
+        get { _keyCommands }
+        set { _keyCommands = newValue }
+    }
+}
+
 class URLBar: ReliefButton
 {
-    let textField = UITextField(frame: .zero)
+    let textField = TextFieldWithKeyCommands(frame: .zero)
     let refreshButton = UIButton(frame: .zero)
     let errorButton = UIButton(frame: .zero)
     let documentButton = UIButton(frame: .zero)
     
+    weak var delegate: URLBarDelegate?
+    
     public enum LoadProgress {
         case complete
         case loading(progress: Double)
@@ -57,6 +73,9 @@ class URLBar: ReliefButton
             // Mask view visibility is affected by editing state.
             self.layoutSubviews()
         }), for: [ .editingDidBegin, .editingDidEnd ])
+        textField.keyCommands = [
+            UIKeyCommand(action: #selector(Self.downKeyPressed), input: UIKeyCommand.inputDownArrow)
+        ]
         addSubview(textField)
         
         textField.addAction(.init(handler: { [textField, refreshButton] _ in
@@ -89,6 +108,11 @@ class URLBar: ReliefButton
         fatalError("init(coder:) has not been implemented")
     }
     
+    @objc
+    private func downKeyPressed(_ sender: Any?) {
+        self.delegate?.urlBarRequestedFocusEscape(self)
+    }
+    
     private func updateProgressIndicator() {
         setErrorButtonAnimating(false)