Question

我有许多视图页面都继承自ContentPage。被调用的第一页从app.cs正确显示工具栏中的图标。第二页（TodoItemView）根本不显示图标（使用相同的代码）。我是否需要做一些事情来初始化第二个视图的工具栏？

提前感谢。

This page is called by the following code:

      var todoList = new TodoListView();
      return new NavigationPage(todoList);

Th page is called by the following code:

      var todoList = new TodoListView();
      return new NavigationPage(todoList);




// Works shows refresh icon
public class TodoListView : ContentPage
    {
        public TodoListView ()
        {
            Title = "Social Events";

            // Display the refresh icon
            var toolbarItem = new ToolbarItem ("Refresh", "refresh.png", ()=>{
            }, 0, 0);
            ToolbarItems.Add (toolbarItem);

            var list = new ListView ();
            var viewModel = new TodoListViewModel ();
            list.ItemsSource = viewModel.TodoList;

            var cell = new DataTemplate (typeof(AspectImageCell));
            cell.SetBinding (TextCell.TextProperty, "Name");
            cell.SetBinding (TextCell.DetailProperty, "Details");
            cell.SetBinding (ImageCell.ImageSourceProperty, "Image");
            list.ItemTemplate = cell;
            list.ItemTapped += (sender, args) => {


                Navigation.PushAsync (new NavigationPage(new TodoItemView ()));

                // Reset the selected item
                list.SelectedItem = null;
            };

            Content = list;
        }
    }

// Does not work, does not show icon
public class TodoItemView : ContentPage
    {
        public TodoItemView ()
        {
            Title = "Todo item";

            var toolbarItem = new ToolbarItem ("Send", "send.png", ()=>{

                // email todo item

            }, 0, 0);
            ToolbarItems.Add (toolbarItem);
         }
}

Answer 1

如果您的应用没有工具栏，则不会显示您的ToolbarItems。添加一个的最简单方法是将页面包装在NavigationPage

中

public static Page GetMainPage ()
{   
    return new NavigationPage(new SamplePage ());
}

Answer 2

您只需要为每个导航堆栈创建一次NavigationPage。当你按下TodoItemView时，请改为：

list.ItemTapped += (sender, args) => {
  Navigation.PushAsync (new TodoItemView ());
  // Reset the selected item
  list.SelectedItem = null;
};

TodoItemView将被推送到第一个NavigationPage中已包含的导航堆栈。消除额外的NavigationPage也可能会修复您丢失的工具栏项。如果没有，还要验证您指定的工具栏图标是否有效。

Answer 3

添加页面的最简单方法是将页面包装在NavigationPage对象中，然后像这样调用它：

var testPage = new NavigationPage(new TestPage());
Navigation.PushAsync(testPage);

Xamarin表示不在视图上显示的工具栏项

3 个答案: