Affine Transformations
The properties and methods provided by the gesture recognizers work well with a trait common to all graphic objects in iOS: affine transformations. A transformation, speaking generally, changes how we draw something. More technically, transformations indicate how points in one coordinate system map to another. Affine transforms are special, because they maintain parallel lines between the two coordinate systems.
A specific example of how we already use affine transforms may be helpful here. Think of how when you print out a document, you can save paper by using the printer dialog to print two pages of the document on one sheet of physical paper, putting two portrait-oriented pages side by side on one landscape page. To ...
Get iOS 9 SDK Development now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
