[iOS] Hide the keyboard when scroll bookmarks search results.

iphone/Maps/Bookmarks/BookmarksVC.mm

@@ -28,6 +28,7 @@ using namespace std;
 @interface BookmarksVC () <UITableViewDataSource,
                            UITableViewDelegate,
                            UISearchBarDelegate,
+                           UIScrollViewDelegate,
                            MWMBookmarksObserver,
                            MWMLocationObserver,
                            MWMKeyboardObserver,
@@ -859,4 +860,11 @@ using namespace std;
   self.noResultsBottom.constant = -keyboardHeight;
 }
 
+#pragma mark - UIScrollViewDelegate
+
+- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
+{
+  [self.searchBar resignFirstResponder];
+}
+
 @end