iPhone Open Application Development

Image Handling

The UIKit framework makes working with images a painless endeavor. With its repertoire of image handling classes, you'll be able to display, scale, clip, and layer images to deliver just the right effects for your application. Rather than bloating out a single image class with obfuscated routines, Apple's developers took the smarter path and subclassed each type of image transformation, with each offering at most a few different methods to be concerned about.

The Image Object

The UIImage class encapsulates the actual image. It can be used to draw directly inside a view or act as a container object in more powerful image view classes. The class provides methods to load an image from various sources, set the image's orientation on the screen, and provide information about the image. For simple graphics, UIImage can be used in a view's drawing routines to render images and patterns. It's an intermediary between the larger, complete image view classes and working with low-level graphics routines, such as raw Core Surface buffers.

A UIImage object can be created from a file, taken from a snapshot of a core surface buffer, or even imported from the desktop wallpaper. Both static and instance methods exist; these can either reference and cache images or instantiate new image objects, depending on the needs of your application.

Static methods

The easiest way to reference an image is through UIImage's static methods. Rather than managing instances of images, the static methods ...