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我一直在关注http://goo.gl/ct7ui上关于“如何：为 Windows Phone 保留和恢复页面状态”的本教程，其中一行代码是这样的：

protected override void OnNavigatedFrom(System.Windows.Navigation.NavigationEventArgs e)
{
    // If this is a back navigation, the page will be discarded, so there
    // is no need to save state.
if (e.NavigationMode != System.Windows.Navigation.NavigationMode.Back)
{
    // Save the ViewModel variable in the page's State dictionary.
    State["ViewModel"] = _viewModel;
}
}

但是，Visual Studio 似乎不喜欢这段代码，给我以下错误：

'System.Windows.Navigation.NavigationEventArgs' does not contain a definition for 'NavigationMode' and no extension method 'NavigationMode' accepting a first argument of type 'System.Windows.Navigation.NavigationEventArgs' could be found (are you missing a using directive or an assembly reference?)

关于我在这里搞砸的任何想法。现在考虑 'e' 是 System.Windows.Navigation.NavigationEventArgs 并且 if 语句之后的位显示 System.Windows.Navigation.NavigationMode.Back，我一辈子都不会看到这是如何给出错误的

4

1 回答 1

2

NavigationMode 是 System.Windows.Navigation 中的枚举。尝试添加

using System.Windows.Navigation;
于 2012-08-31T20:19:15.563 回答