swift - 轻松截断 Double - swift

Question

我希望能够将经度/纬度值 19.3563443 转换为 19.35634(小数点后五位)。有什么简单的方法可以做到这一点吗？

Answer 1

您可以使用NumberFormatter:

extension Formatter {
    static let number = NumberFormatter()
}

---

extension FloatingPoint {
    func fractionDigitsRounded(to digits: Int, roundingMode:  NumberFormatter.RoundingMode = .halfEven) -> String {
        Formatter.number.roundingMode = roundingMode
        Formatter.number.minimumFractionDigits = digits
        Formatter.number.maximumFractionDigits = digits
        return Formatter.number.string(for:  self) ?? ""
    }
}

---

let value = 19.3563443
let roundedToFive = value.fractionDigitsRounded(to: 5) // "19.35634"