Generating smaller previews of selected images from image picker controller

Here is what I am planning:

• user taps on a button.
• a uiimage picker view controller displays
• user selects an image
• a thumbnail view of selected image should be saved in my application. ( like ui picker view has after selecting albums, there is thumbnail view )

Up to three points I can do. But I don't know about creating thumbnail view of selected image.

Undocumented UIImage resizing.