Set your image as lock screen background in Windows 8

Ever wondered how many times we change our wallpapers?? Well I change it everyday! With Windows 8 you can change your lock screen background too. And I can change it everyday because of my App called as National Geographic for Windows 8. And this is how I did it in xaml,

StorageFile file = await StorageFile.CreateStreamedFileFromUriAsync(URI), new Uri(URI),
                RandomAccessStreamReference.CreateFromUri(new Uri(URI)));
            await LockScreen.SetImageFileAsync(file);
            MessageDialog md = new MessageDialog("This image is set as your lock screen background", "Hurray");
            var result = await md.ShowAsync();

this code snippet would set an image from a uri and display a friendly message to the user.
you will have to include
using Windows.Storage.Streams;

using Windows.System.UserProfile;

to use the LockScreen class. LockScreen.SetImageFileAsync accepts a StorageFile object that contains a new image for the lock screen.
Now you can create an app on your own or download my app and get beautiful wallpapers and lock screen backgrounds everyday! Happy Coding!