Advanced Gesture Handling

Two fingers on a photo can do three things at the same moment: move it, zoom it and turn it. A single touch might also be one of several gestures, such as a single tap or the first half of a double tap. Both situations raise one question, which is how several gestures on the same view should relate to one another.

This lesson answers that question while building a photo viewer. It adds pinch and rotation, then combines them with the pan you already know.

Pinch and Rotation

A pinch tracks two fingers moving apart or together. Its event has a `scale