迭代 Swift 扩展中的可用类？

Question

我以前从未尝试过的事情，但我有一个如下所示的扩展（为简洁起见），我希望能够在代码中绘制出每种可用的颜色。我以前从未尝试过，并且无法将正确的搜索词组合在一起甚至接近。想法，指针？

我想以某种方式让let availableColors: [UIColor] = magicalFunctionHere(pointing 扩展）....

我想我必须创建自己的函数并手动插入扩展中的 UIColors。不过，我更愿意自动执行此操作。

extension UIColor {
    class func firstColor ( alpha: CGFloat = 1.0 ) -> UIColor {
        return  UIColor.init ( red: 139.0/255.0, green: 322.0/255.0, blue: 405.0/255.0, alpha: alpha )
    }

    class func secondColor ( alpha: CGFloat = 1.0 ) -> UIColor {
        return  UIColor.init ( red: 225.0/255.0, green: 139.0/255.0, blue: 127.0/255.0, alpha: alpha )
    }
}

Answer 1

这是使用 Obj-C 运行时方法的代码（注意 @objc 前缀，它们是使运行时“看到”您的方法所必需的）：

import Foundation
import XCPlayground
import UIKit

extension UIColor {
    @objc class func fancyColorFirst ( alpha: CGFloat = 1.0 ) -> UIColor {
        return UIColor.red.withAlphaComponent(alpha)
    }

    @objc class func fancyColorSecond ( alpha: CGFloat = 1.0 ) -> UIColor {
        return UIColor.blue.withAlphaComponent(alpha)
    }
}

func methods(in c: AnyClass, where condition: (String) -> Bool ) -> [String] {
    var count: UInt32 = 0
    guard let foundMethods = class_copyMethodList(object_getClass(c), &count) else { return [] }

    let totalMethods = Int(count)
    var matches = [String]()

    for index in 0..<totalMethods {
        let method: Method = foundMethods[index]
        let selector: Selector = method_getName(method)
        let methodName = String(_sel:selector)
        if condition(methodName) {
            matches.append(methodName)
        }
    }
    return matches
}

print(methods(in: UIColor.self, where: { $0.hasPrefix("fancyColor")}))