Rotate UIView with anchorPoint

UIViewRotate.playground

//: Playground - noun: a place where people can play

import UIKit

let r = UIView(frame: CGRect(
    x: 0,
    y: 0,
    width: 200,
    height: 200
))

let posX: CGFloat = 100
let posY: CGFloat = 80
let size: CGFloat = 40

func makeView(color: UIColor) -> UIView {
    let frame = CGRect(
        x: posX,
        y: posY,
        width: size,
        height: size
    )
    let view = UIView(frame: frame)
    r.addSubview(view)
    view.backgroundColor = color
    return view
}

let fondo = makeView(color: .lightGray)
let azul = makeView(color: .blue)
let rojo = makeView(color: .red)

// El anchorPoint también es desde donde se dibuja, así que vamos a cambiarle el center para que calce con el original
azul.center = azul.frame.origin
azul.layer.anchorPoint = .zero

import PlaygroundSupport
PlaygroundPage.current.liveView = r
UIView.animate(
    withDuration: 2.0,
    delay: 0.0,
    options: [.repeat, .autoreverse],
    animations: ({
        azul.transform = azul.transform.rotated(by: CGFloat.pi)
        rojo.transform = rojo.transform.rotated(by: CGFloat.pi)
    }),
    completion: nil
)