Retrieving Transform Properties
When working with transforms, iOS can provide an affine representation of the transform associated with a view. This representation will not, however, tell you exactly how much the view has been scaled or rotated. Recipe 4-5 addresses this problem by calculating the scale and rotation via a simple UIView category.
An affine matrix is stored in iOS as a structure of six fields: a, b, c, d, tx, and ty. Figure 4-4 shows how these values relate to their positions in the standard affine matrix. Simple math allows you to derive scaling and rotation from these, as shown in Recipe 4-5. Note how you can retrieve the tx and ty values directly from the transform. If linear algebra isn’t in your wheelhouse, don’t worry; you ...
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