iOS 9 SDK Development

What We’ve Learned

In this chapter, we took hold—literally—of the touch gestures that are the hallmark of iOS user interfaces. By giving the user the ability to manipulate an image by dragging it around with one finger and pinch-zooming it with two, we immediately create a sense of close contact with the image. Gesture recognizers make it easy to pick up the most common touch gestures and have them call back to our code when gestures are detected. And because both the recognizers and the onscreen views are concerned with how much movement or scaling is indicated by a gesture, it works well to connect the two by means of affine transforms, which ...