Свифт 3:
static func imageFromColor(color: UIColor, width: CGFloat, height: CGFloat) -> UIImage {
let rect = CGRect(x: 0, y: 0, width: width, height: height)
UIGraphicsBeginImageContext(rect.size)
let context = UIGraphicsGetCurrentContext()!
context.setFillColor(color.cgColor)
context.fill(rect)
let img = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return img
}
let button = UIButton(type: .system)
let image = imageFromColor(color: .red, width:
button.frame.size.width, height: button.frame.size.height)
button.setBackgroundImage(image, for: .normal)