How to apply multiple transforms in Swift
You can apply multiple transforms by stacking them on top of each other.
var t = CGAffineTransform.identityt = t.translatedBy(x: 100, y: 300)t = t.rotated(by: CGFloat.pi / 4)t = t.scaledBy(x: -1, y: 2)// ... add as many as you want, then apply it to to the viewimageView.transform = t
Or more compactly (but not necessarily as readable):
imageView.transform = CGAffineTransform.identity.translatedBy(x: 100, y: 300).rotated(by: CGFloat.pi / 4).scaledBy(x: -1, y: 2)
This series of transforms produces the image on the right:
Thanks to this answer for teaching me how to do it.
Notes
The order in which you apply the transforms matters. For example, if the transforms were done in the opposite order it would produce the following result.
t = t.scaledBy(x: -1, y: 2)t = t.rotated(by: CGFloat.pi / 4)t = t.translatedBy(x: 100, y: 300)
See also
- CGAffineTransform Reference (docs)
- Transforms (docs)
- Swift: Translating and Rotating a CGContext, A Visual Explanation (iOS/Xcode)
- Demystifying CGAffineTransform
This answer has been tested with Swift 4
In Swift 3, these have been replaced by functions on CGAffineTransform itself, which can be chained.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)