我的代码中有自定义颜色.我多次使用它们,我想只分配一次.

情况/问题

如果我们看一下UIColor标题,我们可以看到以下内容:

[...]

// Some convenience methods to create colors.  These colors will be as calibrated as possible.
// These colors are cached.

open class var black: UIColor { get } // 0.0 white

open class var darkGray: UIColor { get } // 0.333 white

[...]

我创建了一个extensionUIColor,如下所示:

import UIKit

extension UIColor {

    class func colorWithHexString(_ hex: String) -> UIColor {

        print("\(#function): \(hex)")

        // some code, then it return a UIColor

        return UIColor(
            red: CGFloat((rgbValue & 0xFF0000) >> …