c# - 将 await 与 MessageDialog.ShowAsync() 一起使用时出错

Question

在一个方法中我有一个 try catch像这样阻止:

try
{
    // do something
}
catch (Exception ex)
{
    MessageDialog message = new MessageDialog(ex.ToString());
    message.ShowAsync();
}

我收到以下关于 message.ShowAsync() 行的警告:

Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call.

说完了:

try
{
    // do something
}
catch (Exception ex)
{
    MessageDialog message = new MessageDialog(ex.ToString());
    await message.ShowAsync();
}

现在我得到一个异常(exception):

The 'await' operator can only be used within an async method. Consider marking this method with the 'async' modifier and changing its return type to 'Task'.

我什至尝试这样做以避免在 catch block 内等待:

Exception exception;
try
{
    // do something
}
catch (Exception ex)
{
    exception = ex;
}

if (exception != null)
{
    MessageDialog message = new MessageDialog(ex.ToString());
    message.ShowAsync();
}

然而，这并没有改变任何东西。

我必须做什么才能使用 await在这种情况下？ MessageDialog.ShowAsync()就 IntelliSense 显示返回 Windows.Foundation.IAsyncOperation<IUICommand> 的可等待方法而言.

Answer 1

您的函数必须是“异步的”才能使用异步运算符:

例如:

 private async void Test()
 {
    MessageDialog message = new MessageDialog(ex.ToString());
    await message.ShowAsync();
 }