使用字符串通过键访问类扩展中struct中的静态变量

Question

The goal is to access a static variable in a struct in a class extension:

extension UIColor {
    struct MyColors {
        static var happy: UIColor {
            return UIColor(hexString: "#FFB100")!
        }
        static var superHappy: UIColor {
            return UIColor(hexString: "#FFB101")!
        }

        static func withName(_ name: String = "") -> UIColor? {
            return UIColor.value(forKey: name) as? UIColor
        }
    }
}

// Produces error "this class is not key value coding-compliant for the key happy."
let myHappyColor = UIColor.MyColors.withName("happy")

Can we do something like that in PHP ?

<?php
$prop = 'Name';
echo $obj->$prop;

Answer 1

You can use either static variables or enumeration:

extension UIColor {

    // MARK: - Static

    static let myColor = UIColor(/* setup */)

or

enum MyColors {
case red

var color: UIColor {
switch self {
case .red:
return .red
}
}

Answer 2

You can create Color set in xcassets catalog with some name. Then, you can initalize color from this set using designed initalizer

UIColor(named: "Name")

---

Anyway, in Swift you should avoid initalizing objects with identifiers (I'm not talking about named sets but about your current approach). Swift is safe-type language. Try to obey rules of safe-type language.