How to change size of thumb image of UISlider programmatically

Question

I would like to make the custom UISlider, something like this

|o----------| -> |-----O------| -> |------------〇|

the thumbImage will be small at

Answer 1

Swift 3:

extension UIImage {

    func scaleToSize(newSize: CGSize) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0)
        draw(in: CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height))
        let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext();
        return newImage
    }
}