c# – 显示Windows 10 Toast通知

// Get a toast XML template
XmlDocument toastXml = ToastNotificationManager.GetTemplateContent(ToastTemplateType.ToastImageAndText04);

// Fill in the text elements
XmlNodeList stringElements = toastXml.GetElementsByTagName("text");
for (int i = 0; i < stringElements.Length; i++)
{
    stringElements[i].AppendChild(toastXml.CreateTextNode("Line " + i));
}

// Specify the absolute path to an image
String imagePath = "file:///" + Path.GetFullPath("toastImageAndText.png");
XmlNodeList imageElements = toastXml.GetElementsByTagName("image");
imageElements[0].Attributes.GetNamedItem("src").NodeValue = imagePath;

// Create the toast and attach event listeners
ToastNotification toast = new ToastNotification(toastXml);
toast.Activated += ToastActivated;
toast.Dismissed += ToastDismissed;
toast.Failed += ToastFailed;

// Show the toast. Be sure to specify the AppUserModelId on your application's shortcut!
ToastNotificationManager.CreateToastNotifier(APP_ID).Show(toast);

测试完这段代码后,我想将它实现到我的应用程序中.所以我稍微改了一下并尝试运行它.错误消息：

The type “IReadOnlyList<>” is defined in a not referenced assembly. Add a reference to System.Runtime,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a”
(translated)

IEnumerable<>也是如此和IReadOnlyList<>

错误来自这两行：

for (int i = 0; i < stringElements.Length; i++)
{
    stringElements[i].AppendChild(toastXml.CreateTextNode("Line " + i));

我也尝试添加对System.Runtime的引用.我用NuGet(https://www.nuget.org/packages/System.Runtime/4.0.0/)下载了它.
之后错误消失了,但现在我的代码中的每个单词都被淹没了红色,出现错误,例如“System.Object未定义”等等(但是当我启动它时它仍会运行！).

我能想到的唯一可能的解决方案是System.Runtime已经安装在我的计算机上的某个地方,并且4.0.0是我程序的错误版本.但我无法在任何地方找到它.

PS：这是桌面应用程序,而不是Windows应用程序.