【Swift】UIImageの色を変える（塗りつぶす） ref: https://qiita.com/ryokosuge/items/d5389866f4403771ae76

UIImageExtension.swift

extension UIImage {
    func tint(color: UIColor) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        color.setFill()
        let drawRect = CGRectMake(0, 0, size.width, size.height)
        UIRectFill(drawRect)
        drawInRect(drawRect, blendMode: kCGBlendModeDestinationIn, alpha: 1)
        let tintedImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return tintedImage
    }
}