Handling User Touches

Abstract

The iPhone was a drastic change from every computing platform that came before it in many ways, but none more so than its lack of a mouse or keyboard. Instead of responding to keyboard key presses, mouse clicks, and mouseover events, the iPhone responds to touch. Designing a user interface around touch is more than converting from clicks to taps. The iPhone offers direct manipulation: when you place your finger on a message in Mail and move it down an inch, the contents of the message move down an inch as well. Direct manipulation effectively removes a layer of abstraction between the user and the content dating back to the very first graphical user interfaces (GUIs): the scroll bar. As a result, iOS and other touchscreen operating systems are easier to use and more intuitive than their desktop predecessors. This chapter will show you how you can use touch in your apps, transforming a stale user experience into a rich, immersive app that users will love. We#x2019;ll talk about various ways you can make your application respond to user touches, including custom views and gesture recognizers, as well as update our MyStuff example app with some new user interface elements.