图像按钮上的色调快速Xcode

Question

我想在我的Xcode project.Suggest上的按钮，添加35％的透明色彩与图像我该怎么做我的情况

我的代码：

// Button
        let aButt = UIButton(type: .custom)
        aButt.frame = CGRect(x: X, y: Y, width: W, height: H)
        aButt.tag = i
        aButt.setTitle("\(peObj[EVENTS_TITLE]!)", for: .normal)
        aButt.contentVerticalAlignment = .bottom
        aButt.titleLabel?.font = UIFont(name: "OpenSans-Bold", size: 13)
        aButt.setTitleColor(UIColor.white, for: .normal)
        aButt.addTarget(self, action: #selector(popularEventButt(_:)), for: .touchUpInside)
        getParseImage(object: peObj, colName: EVENTS_IMAGE1, button: aButt)
        aButt.imageView?.contentMode = .scaleAspectFill
        aButt.clipsToBounds = true
        aButt.backgroundColor = UIColor.lightGray
        aButt.layer.cornerRadius = 8