No installed components were detected. Element is already the child of another element

问题

In App.xaml I have added Application Resources with a button as:

 <Application.Resources>
    <Button x:Key="MyButton"/>
</Application.Resources>

In MainPage.xaml.cs, I tried to add this button programatically in my grid.

 Button btn = (Button)Application.Current.Resources["MyButton"];
 myGrid.Children.Add(btn);

But it gives error like this:

No installed components were detected. Element is already the child of another element.

In MainPage.xaml:

 <Grid x:Name="myGrid" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

</Grid>

I don't know what I'm doing wrong.

Thanks.

回答1:

You cannot add the element that is already child of another element. It's like your child cannot be the child of another guy man.

回答2:

This exception is usually thrown if you're using more than one instance of the control you defined in your application resources. If that is the case, you should do:

<Button x:Key="MyButton" x:Shared="false"/>

EDIT: it seems WInRT doesn't support x:shared attribute.

There is a workaround using ControlTemplates: http://www.gdomc.com/0428/binding-the-content-property-of-a-contentcontrol-in-winrt/

来源：https://stackoverflow.com/questions/38184819/no-installed-components-were-detected-element-is-already-the-child-of-another-e