Mac OS X includes a wide variety of features and assistive technologies known as Universal Access that include screen and cursor magnification, a full-featured screen reader, visual flash alerts, closed-captioning support, and much more. Mac OS X includes all the features your application needs to make it accessible to users with special needs.
Making Your App Accessible
Apple Human Interface Guidelines provide detailed instructions on how to create an intuitive interface that enables users with disabilities to accomplish tasks quickly and efficiently, while maintaining the consistency and ease of learning that characterizes successful Mac applications. Developers using standard controls and their subclasses will find support for assistive applications is built-in. Apple’s Accessibility APIs define how Mac OS X applications can make their user interface available to an external assistive application or service.
Apple strongly encourages developers to support these APIs in all of their applications so they are compatible with features built into Mac OS X such as VoiceOver, as well as other third-party products. The Xcode and Interface Builder tools, as well as the Cocoa frameworks, make it easy to add accessibility tags like roles and descriptions. For example, Interface Builder has an Inspector that allows you to enter a description for any control in the user interface; that description will be synthesized into speech when VoiceOver is enabled.
How it Works
An assistive application interacts with accessibility objects in your application to allow people with disabilities to drive the user interface in non-traditional ways. For example, a VoiceOver user relies solely on the keyboard for control, and on Speech Synthesis for feedback.  If your application can only be used with a mouse, it will be inaccessible to a user who relies on VoiceOver and other applications that use the Accessibility APIs in Mac OS X. Users with low vision can also set Mac OS X’s built-in zoom, grayscale, and white-on-black display mode options to adapt the onscreen experience to their specific needs. Those who are deaf or hard of hearing can set audible alerts to automatically flash the screen instead. Physically disabled users will rely on AppleScript and Automator workflows to simplify complex tasks and can take advantage of keyboard and mouse preferences to make them easier to control and use.  It is important that your application work as intended for those who rely on these assistive features of Mac OS X.
Through Universal Access, Accessibility APIs that support technologies such as Speech Recognition, Speech Synthesis, AppleScript, and Voiceover, and a host of developer tools and utilities, Mac OS X provides an extraordinary opportunity to deliver a superior computing experience to every customer, including those with special needs
