How to apply multiple transforms in Swift

Question

I would like to apply multiple transforms to a UIView (or subclass of UIView), such as translate, rotate, and scale. I know that two transforms can be applied with CGAffineTransformConcat, but how do I do it if I have three or more transforms?

I have seen these questions:

• Applying multiple transforms to a UIView / CALayer
• Using Multiple CGAffineTransforms On Text Matrix

but these questions are asking something different, and the given answers just talk about applying two transforms with CGAffineTransformConcat. Also, they use Objective-C rather than Swift.

Answer 1

In Swift 3, these have been replaced by functions on CGAffineTransform itself, which can be chained.

extension CGAffineTransform {
    public func translatedBy(x tx: CGFloat, y ty: CGFloat) -> CGAffineTransform
    public func scaledBy(x sx: CGFloat, y sy: CGFloat) -> CGAffineTransform
    public func rotated(by angle: CGFloat) -> CGAffineTransform
}

so for example

let transform = CGAffineTransform(scaleX: 1.0, y: 3.0).translatedBy(x: 12, y: 9).rotated(by: 17.0)

Answer 2

the trick is that view.transform.translatedBy(x: 100, y: 100) is NOT changing view.transform. it just returns the new CGAffineTransform that you need to ASIGN back to view.transform.

view.transform = view.transform.translatedBy(x: 100, y: 100)

You can do that as many times as you need or in a sequence

view.transform = view.transform.translatedBy(x: 100, y: 100).rotated(by: CGFloat.pi / 2).scaledBy(x: 2, y: 2)