         }
         return _removeNavigationTitleActionItemButton(at: _navigationTitleActionItems.index(before: _navigationTitleActionItems.endIndex))
     }
-    // MARK: - Selected title.
+    // MARK: - Selecte Title Item.
     public func setSelectedTitle(at index: Int, animated: Bool) {
         guard index >= _navigationTitleItems.startIndex && index < _navigationTitleItems.endIndex else {
             return

        
        return removeNavigationItem(at: _navigationItems.index(before: _navigationItems.endIndex))
    }
    
    public func addNavigationTitleItem(_ item: TabNavigationTitleItem) {
        _addNavigationTitleItemButton(item)

}

extension TabNavigationBar {
    // MARK: - Public Property.
    
    /// Get the selected title item of the tab-navigation bar.
    public var selectedTitleItem: TabNavigationTitleItem? {
        guard _earlyCheckingIndex(_selectedTitleItemIndex, in: _navigationTitleItems) else {
