Get just the scaling transformation out of CGAffineTransform
Assuming that the transformation is a scaling followed by a rotation (possibly with a translation in there, but no skewing) the horizontal scale factor is sqrt(a^2+c^2), the vertical scale factor is sqrt(b^2+d^2), and the ratio of the horizontal scale factor to the vertical scale factor should be a/d = -c/b, where a, b, c, and d are four of the six members of the CGAffineTransform, per the documentation (tx and ty only represent translation, which does not affect the scale factors).
| a b 0 || c d 0 || tx ty 1 |
- (CGFloat)xscale { CGAffineTransform t = self.transform; return sqrt(t.a * t.a + t.c * t.c);}- (CGFloat)yscale { CGAffineTransform t = self.transform; return sqrt(t.b * t.b + t.d * t.d);}
That is an old question, but I still add more information in case someone needs.
For me, the good answer and sample code for getting scale, rotation of transformation and for reproducing it are from article: