Swift DateComponentsFormatter删除前导零，但在Minutes位置至少保留一位数字 [英] Swift DateComponentsFormatter drop leading zeroes but keep at least one digit in Minutes place

问题描述

我在Swift中使用以下DateComponentsFormatter：

I am using the following DateComponentsFormatter in Swift:

let formatter = DateComponentsFormatter()
formatter.unitsStyle   = .positional
formatter.allowedUnits = [.hour, .minute, .second]
formatter.zeroFormattingBehavior = [.default]

这将产生类似于2:41（2分41秒）和08（8秒）的结果。但是，我想在Minutes位置至少保留一位数字，返回0:08而不是08。DateComponentsFormatter是否可能？我希望有一个返回本地化结果的解决方案。

This produces results like 2:41 (for 2 minutes and 41 seconds) and 08 (for 8 seconds). I would, however, like to keep at least one digit in the Minutes place, returning 0:08 instead of 08. Is this possible with the DateComponentsFormatter? I would prefer a solution that returns a localized result.

推荐答案

是。设置日期组件格式化程序允许的单位时，可以很容易地实现基于时间间隔的三元条件添加。

Yes. This can be easily accomplished adding a ternary conditional based on the time interval when setting the date components formatter allowed units:

Xcode 11•Swift 5.1

extension Formatter {
    static let positional: DateComponentsFormatter = {
        let positional = DateComponentsFormatter()
        positional.unitsStyle = .positional
        positional.zeroFormattingBehavior = .pad
        return positional
    }()
}

---

---

extension TimeInterval {
    var positionalTime: String {
        Formatter.positional.allowedUnits = self >= 3600 ?
                                            [.hour, .minute, .second] :
                                            [.minute, .second]
        let string = Formatter.positional.string(from: self)!
        return string.hasPrefix("0") && string.count > 4 ?
            .init(string.dropFirst()) : string
    }
}

---

用法

---

Usage

8.0.positionalTime     //    "0:08"
161.0.positionalTime   //    "2:41"
3600.0.positionalTime  // "1:00:00"

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