如何更新WP8应用程序中的复选框

Question

In my wp8 app, I have check box which is under a listbox.

Here is the XAML code:

 <ListBox Name="URLListBox"  Grid.Row="2"  >
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid   >
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition/>
                            <ColumnDefinition Width="400"/>

                        </Grid.ColumnDefinitions>

                            <TextBlock   Grid.Column="1" Tag="{Binding b1Tag}" Tap="surenameTap"   x:Name="surename" FontFamily="Consolas"  FontSize="25" Text="{Binding text}"   VerticalAlignment="Center" HorizontalAlignment="Center" Margin="60,0,0,0"/>


                        <CheckBox IsEnabled="False"  BorderThickness="0" BorderBrush="DarkGreen"  Background="DarkGreen"  Grid.Column="0" x:Name="checkbox" IsChecked="{Binding file}"   ></CheckBox>

                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

I want to update the checkbox while program is working. The checkbox shows if the data is downloaded or not.

I use BackgroundTransferRequest to download the file. I want the checkbox to be checked when download is finished.

Actually I have class that determines which files are downloaded and I bind it with the checkbox, but it changes the checkbox when I enter the page. That is I should go to previous menu and restart the page that contains checkboxes, then it shows which checkboxes are checked, but I want that when I am in page.

Here is the class that binds the checkbox:

lnk = new linkname();
URLListBox.ItemsSource = lnk.obj();

Answer 1

Make sure that you have set the DataContext and Implemented InotifyPropertyChanged Interface, Only when You implement the interface the property will get updated.

And also you have to add Mode="TwoWay" when binding, something like this

IsChecked="{Binding file, Mode="TwoWay"}"

A quick sample is here