Finish implementing autocomplete keyboard nav

App/Autocomplete/AutocompleteViewController.swift

@@ -67,6 +67,53 @@ class AutocompleteViewController: UIViewController, UICollectionViewDelegate
         self.view = autocompleteView
     }
     
+    override var keyCommands: [UIKeyCommand]? {
+        [
+            UIKeyCommand(action: #selector(self.selectNextItem), input: UIKeyCommand.inputDownArrow),
+            UIKeyCommand(action: #selector(self.selectPreviousItem), input: UIKeyCommand.inputUpArrow),
+            UIKeyCommand(action: #selector(self.commitSelectedItem), input: "\r"), // this is stupid... 
+        ]
+    }
+    
+    override func becomeFirstResponder() -> Bool {
+        let result = super.becomeFirstResponder()
+        if result {
+            let firstIndex = IndexPath(row: 0, section: 0)
+            collectionView.selectItem(at: firstIndex, animated: false, scrollPosition: .top)
+        }
+        
+        return result
+    }
+    
+    private func selectItem(inDirection direction: Int) {
+        if let selectedIndex = collectionView.indexPathsForSelectedItems?.first {
+            let nextRow = (selectedIndex.row + direction)
+            if nextRow < dataSource.snapshot().numberOfItems && nextRow >= 0 {
+                let nextIndexPath = IndexPath(row: nextRow, section: 0)
+                collectionView.selectItem(at: nextIndexPath, animated: false, scrollPosition: .centeredVertically)
+            }
+        }
+    }
+    
+    @objc
+    private func selectNextItem(_ sender: Any?) {
+        selectItem(inDirection: 1)
+    }
+    
+    @objc
+    private func selectPreviousItem(_ sender: Any?) {
+        selectItem(inDirection: -1)
+    }
+    
+    @objc
+    private func commitSelectedItem(_ sender: Any?) {
+        if let selectedIndex = collectionView.indexPathsForSelectedItems?.first,
+           let item = dataSource.itemIdentifier(for: selectedIndex)
+        {
+            delegate?.autocompleteController(self, didSelectHistoryItem: item)
+        }
+    }
+    
     // MARK: UICollectionViewDelegate
     
     func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {