Quickly generate images of programmatic colors on the fly.

UIImage+Color.swift

extension UIImageView
    func setImage(withColor color: UIColor) {
        image = UIImage.withColor(color, size: bounds.size)
    }
}

extension UIImage {
    static func withColor(_ color: UIColor, size: CGSize) -> UIImage {
        let rect = CGRect(origin: CGPoint.zero, size: size)
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        color.setFill()
        UIRectFill(rect)
        let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return image
    }
}