Render a view at 2x scale factor in an Xcode playground

retina_wrap.swift

func retinaWrap(view: UIView, scaleFactor: CGFloat = 2.0) -> UIView {
    let scaleTransform = CGAffineTransformMakeScale(scaleFactor, scaleFactor)
    let scaledView = UIView(frame: CGRectMake(0, 0, view.bounds.width * scaleFactor, view.bounds.height * scaleFactor))
    view.transform = scaleTransform
    view.center = CGPoint(x: scaledView.frame.width / 2, y: scaledView.frame.height / 2)
    scaledView.addSubview(view)
    return scaledView
}