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How to find the rotation from a CGAffineTransform

Paul Hudson       @twostraws

A CGAffineTransform value combines scale, translation and rotation all at once, but if you just want to know its rotation value is then use this code:

func rotation(from transform: CGAffineTransform) -> Double {
    return atan2(Double(transform.b), Double(transform.a))
}

Available from iOS 2.0

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