CGImage objects abstract the data-writing task. An image destination can represent a single image or multiple images. It can contain thumbnail images as well as properties for each image.
The functions described in this reference can write data to three kinds of destinations: a URL, a
CFData object, and a data consumer. After creating a
CGImage object for the appropriate destination, you can add image data and set image properties. When you are finished adding data, call the function
CGImage to write the image data and properties to the URL,
CFData object, or data consumer.