Swift中的精确字符串格式说明符

根据David的回答，到目前为止，我最好的解决方案是

import Foundationextension Int {    func format(f: String) -> String {        return String(format: "%(f)d", self)    }}extension Double {    func format(f: String) -> String {        return String(format: "%(f)f", self)    }}let someInt = 4, someIntFormat = "03"println("The integer number (someInt) formatted with "(someIntFormat)" looks like (someInt.format(someIntFormat))")// The integer number 4 formatted with "03" looks like 004let someDouble = 3.14159265359, someDoubleFormat = ".3"println("The floating point number (someDouble) formatted with "(someDoubleFormat)" looks like (someDouble.format(someDoubleFormat))")// The floating point number 3.14159265359 formatted with ".3" looks like 3.142

我认为这是最类似于Swift的解决方案，将格式化操作直接与数据类型相关联。可能是某处有一个内置的格式化操作库，或者它可能很快就会发布。请记住，该语言仍处于测试阶段。