Swift格式化字符串(如果不是整数)具有2个十进制数字 [英] Swift Formatting String to have 2 decimal numbers if it is not a whole number

问题描述

我有一个要格式化的字符串，当它不是整数时，最多显示两位小数，但如果是整数，则不应该小数位.

I have a string that I would like to be formatted such that when it is not a whole number, it will display up to two decimal places but if it is a whole number, there should be no decimal places.

是否有更简便的方法快速完成此操作，还是我必须满足于if-else?

Is there an easier way to do this in swift or do I have to settle for an if-else?

推荐答案

您可以扩展FloatingPoint来检查它是否为整数，并使用条件将NumberFormatter的minimumFractionDigits属性设置为0，如果是这样，则将其设置为2:

You can extend FloatingPoint to check if it is a whole number and use a condition to set the minimumFractionDigits property of the NumberFormatter to 0 in case it is true otherwise set it to 2:

extension Formatter {
    static let custom: NumberFormatter = {
        let formatter = NumberFormatter()
        formatter.numberStyle = .decimal
        formatter.maximumFractionDigits = 2
        return formatter
    }()
}
extension FloatingPoint {
    var isWholeNumber: Bool { isNormal ? self == rounded() : isZero }
    var custom: String {
        Formatter.custom.minimumFractionDigits = isWholeNumber ? 0 : 2
        return Formatter.custom.string(for: self) ?? ""
    }
}

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游乐场测试:

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Playground testing:

1.0.custom    // "1"
1.5.custom    // "1.50"
1.75.custom   // "1.75"

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