NSAffine class provides methods for creating, concatenating, and applying affine transformations.
A transformation specifies how points in one coordinate system are transformed to points in another coordinate system. An affine transformation is a special type of transformation that preserves parallel lines in a path but does not necessarily preserve lengths or angles. Scaling, rotation, and translation are the most commonly used manipulations supported by affine transforms, but shearing is also possible.
Methods for applying affine transformations to the current graphics context and a method for applying an affine transformation to an
NSBezier object are described in NSAffineTransform Additions Reference in the Application Kit.