Learning iOS Development: A Hands-on Guide to the Fundamentals of iOS Programming

Custom Recognizers

In the last section, you added a built-in recognizer to the CarValet app. The next step is to add a custom recognizer. Before doing that, you need to understand more about how recognizers work.

Recognizers are state machines, flowing through four states for single-gesture recognizers and through seven for continuous ones. You update state and implement the gesture behavior by specializing one or more UIGestureRecognizer messages.