The iPhone 4 (and 4S) (as well as the iPad 2) has a camera (in fact two - one front facing and one rear facing) that enables users to both take pictures and record videos. These pictures and videos are saved in the Photos application. As a developer, you have two options to manipulate the camera and to access the pictures and videos stored in the Photos application:
Every iOS device includes the Photos application, in which pictures are stored. Using the iOS SDK, you can use the UIImagePickerController class to programmatically display a UI that enables users to select pictures from the Photos application. The following Try It Out demonstrates how you can do that in your application.
TRY IT OUT: Accessing the Photos in the Photo Library