swift有类级静态变量吗？

Question

如何在类范围中声明静态常量？如

class let Constant: Double = 3.1415926
// I know that in class we use class modifier instead of static.

Answer 1

Swift支持静态类型属性,包括类,从Swift 1.2开始:

class MyClass {
    static let pi = 3.1415926
}

如果需要在子类中具有可覆盖的类变量,则需要使用计算的类属性:

class MyClass {
    class var pi: Double { return 3.1415926 }
}

class IndianaClass : MyClass {
    override class var pi: Double { return 4 / (5 / 4) }
}