UIImage+AnimationSequence.swift

public extension UIImage {
  /**
     Example:
     ```
     UIImage.animationSequence(withPattern: "0XX_animation_images", swapMatching: "XX", numberOfImages: 60)
     ```

     @param base The base string on which the animation image sequence will be generated. Note: Must have *match* embeded inside.
     @param match: The pattern contained in pattern that will be substituted.
     @param count: number of images to be generated. Note: Must be less than or equal to log 10 of match length.
    */
    static func animationSequence(withBase base: String,
                                  swapMatching match: String,
                                  numberOfImages count: Int) -> [UIImage] {

        func curriedName(base: String, match: String) -> (String) -> String {
            return { replacement in
                return base.replacingOccurrences(of: match, with: replacement)
            }
        }
        let baseString = curriedName(base: base, match: match)
        var images: [UIImage] = []
        let baseNumber = match.characters.count

        for i in 0..<count {
            let numberOf0s = baseNumber - Int(floor(log10(Double(i)))) + 1
            let zeros = Array(repeating: "0", count: numberOf0s).reduce("", +)
            if let image = UIImage(named: baseString(zeros + "\(i)")) {
                images.append(image)
            }
        }
        return images
    }
}