C# 如何在windows phone 8.1中显示特定的透视项目

我在一个页面上有两个数据透视项，我想基于上一个页面按钮显示特定的数据透视项。我有两个名为“联系人”和“帮助”的按钮。我想当用户单击联系人按钮时，项目1首先显示，当用户单击帮助项目时，首先显示。如何做到这一点

这是我的xaml

<Pivot x:Name="MyPivot">
         <PivotItem x:Name="contact" >
                <PivotItem.Header>
                    <TextBlock FontFamily="Assets/fonts/KBPlanetEarth.ttf#KBPlanetEarth" Foreground="Purple" Margin="0,20,0,0">Contact</TextBlock>
                </PivotItem.Header>
                <StackPanel>
                <Image VerticalAlignment="Top" Width="250" Height="150" HorizontalAlignment="Left" Source="Assets/icons/logo.png"></Image>
                    <TextBlock Foreground="Black" FontFamily="Comic Sans MS" TextWrapping="Wrap" FontSize="20">Feel Free to contact for any errors,updates and for don't forget to review.</TextBlock>
                    <Button Click="Button_Click" Height="80" Width="180" Margin="0,10,0,0"   FontFamily="Assets/fonts/Arista2.0.ttf#Arista 2.0" Background="#27aae0" FontSize="25" Content="Email" Foreground="White" HorizontalAlignment="Center" VerticalAlignment="Center" ></Button>
                    <Button Click="Button_Click_1" Height="80" Width="180" Margin="0,10,0,0"   FontFamily="Assets/fonts/Arista2.0.ttf#Arista 2.0" Background="#27aae0" FontSize="25" Content="Facebook" Foreground="White" HorizontalAlignment="Center" VerticalAlignment="Center" ></Button>
                    <Button Click="Button_Click_2" Height="80" Width="180" Margin="0,10,0,0"   FontFamily="Assets/fonts/Arista2.0.ttf#Arista 2.0" Background="#27aae0" FontSize="25" Content="Review" Foreground="White" HorizontalAlignment="Center" VerticalAlignment="Center" ></Button>

                </StackPanel>
            </PivotItem>
            <PivotItem x:Name="helped" >
                <PivotItem.Header>
                    <TextBlock FontFamily="Assets/fonts/KBPlanetEarth.ttf#KBPlanetEarth" Foreground="Purple" Margin="0,20,0,0">Help</TextBlock>
                </PivotItem.Header>

                <FlipView>
                    <FlipViewItem>
                        <Image Source="Assets/7.png"></Image>
                    </FlipViewItem>
                    <FlipViewItem>
                        <Image Source="Assets/15.png"></Image>

                    </FlipViewItem>

                </FlipView>

            </PivotItem>
        </Pivot>

接触
如有任何错误、更新，请随时联系，不要忘了查看。
帮助

您可以通过更改MyPivot.SelectedIndex的值来更改显示的项目