Get just the scaling transformation out of CGAffineTransform

Question

I found a similar question about getting just the rotation, but as I understand scaling and rotating work different in the transform matrix.

Matrixes are not my strength

Answer 1

Swift 4 Extension (thanks to Robin Macharg's answer)

extension CGAffineTransform
{
    var xScale: CGFloat { return sqrt(a * a + c * c) }
    var yScale: CGFloat { return sqrt(b * b + d * d) }
    var rotation: CGFloat { return CGFloat(atan2(Double(b), Double(a))) }
    var xOffset: CGFloat { return tx }
    var yOffset: CGFloat { return ty }
}

Note that CGFloat equals a Double on most platforms, thus conversions need to be to Double.