使用MasterDetailPage或ToolbarItem會在Xamarin.Forms上引發異常

Question

Xamarin.Forms可移植庫XAML項目中有以下兩個XAML代碼：

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="TestApp.Views.TestView">
  <ContentPage.ToolbarItems>
    <ToolbarItem Text="{Binding ToolbarItemText}" Command="{Binding ToolbarItemCommand}" Order="Default" Priority="0"/>
  </ContentPage.ToolbarItems>
  <ContentPage.Content>
  </ContentPage.Content>
</ContentPage>

和

<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="TestApp.Views.Test2View">
  <MasterDetailPage.Master>
    <ContentPage Title="Currencies">

    </ContentPage>
  </MasterDetailPage.Master>
  <MasterDetailPage.Detail>
    <NavigationPage>
      <x:Arguments>
        <ContentPage>
        </ContentPage>
      </x:Arguments>
    </NavigationPage>
  </MasterDetailPage.Detail>
</MasterDetailPage>

運行Windows Phone 8.1項目（WinRT，而不是Silverlight）時，我有以下異常：

E_UNKNOWN_ERROR

錯誤HRESULT E_FAIL已從對COM組件的調用返回。

Answer 1

問題是，你必須指定MasterDetailPage.Master頁，而該ToolbarIcon的圖標路徑 。 此外，對於MasterDetailPage.Master頁面，您必須指定Title屬性。

這是更正的代碼示例：

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="TestApp.Views.TestView">
  <ContentPage.ToolbarItems>
    <ToolbarItem Text="{Binding ToolbarItemText}" Command="{Binding ToolbarItemCommand}" Order="Default" Priority="0">
      <ToolbarItem.Icon>
        <OnPlatform x:TypeArguments="FileImageSource"
               Android="my-icon"
               WinPhone="Assets/my-icon.png" />
      </ToolbarItem.Icon>
    </ToolbarItem>
  </ContentPage.ToolbarItems>
  <ContentPage.Content>
  </ContentPage.Content>
</ContentPage>

和

<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="TestApp.Views.Test2View">
  <MasterDetailPage.Master>
    <ContentPage Title="Currencies">
      <ContentPage.Icon>
        <OnPlatform x:TypeArguments="FileImageSource"
               Android="my-icon"
               WinPhone="Assets/my-icon.png" />
      </ContentPage.Icon>
    </ContentPage>
  </MasterDetailPage.Master>
  <MasterDetailPage.Detail>
    <NavigationPage>
      <x:Arguments>
        <ContentPage>

        </ContentPage>
      </x:Arguments>
    </NavigationPage>
  </MasterDetailPage.Detail>
</MasterDetailPage>