可以使用converted和MeasurementFormatter
在最简单的形式中，它看起来像

struct VolumeSampleView: View {
    let volume = Measurement(value: 10, unit: UnitVolume.liters)
    var body: some View {
        Text(volume.converted(to: .milliliters), formatter: MeasurementFormatter())
    }
}

但在extension中，您可以添加可重复使用的自定义，它的工作原理类似于formatted，但允许iOS 14+。

extension Formatter{
    static func measurement(unitOptions: MeasurementFormatter.UnitOptions = .providedUnit, unitStyle: Formatter.UnitStyle = .short, numberStyle: NumberFormatter.Style = .decimal) -> MeasurementFormatter{
        
        let f = MeasurementFormatter()
        f.unitOptions = unitOptions
        f.unitStyle = unitStyle
        
        let nf = NumberFormatter()
        nf.numberStyle = numberStyle
        
        f.numberFormatter = nf
        
        return f
    }
}

然后您的View将演变为类似于

struct VolumeSampleView: View {
    let volume = Measurement(value: 10, unit: UnitVolume.liters)
    let mass = Measurement(value: 10, unit: UnitMass.kilograms)
    var body: some View {
        Text(volume.converted(to: .milliliters), formatter: .measurement())
        Text(mass.converted(to: .grams), formatter: .measurement())

    }
}

您还可以扩展Measurement本身并添加一个自动提供字符串的方法。

extension Measurement{
    func toString(unitOptions: MeasurementFormatter.UnitOptions = .providedUnit, unitStyle: Formatter.UnitStyle = .short, numberStyle: NumberFormatter.Style = .decimal) -> String{
        
        let f = Formatter.measurement(unitOptions: unitOptions, unitStyle: unitStyle, numberStyle: numberStyle)
        return f.string(from: self)
    }
}

然后你不必使用formatter，你可以调用toString()，这将允许一个适用于所有SwiftUI版本的答案。

struct VolumeSampleView: View {
    let volume = Measurement(value: 10, unit: UnitVolume.liters)
    let mass = Measurement(value: 10, unit: UnitMass.kilograms)
    let temp = Measurement(value: 30, unit: UnitTemperature.fahrenheit)
    var body: some View {
        VStack{
            Text(volume.converted(to: .milliliters).toString())
            Text(volume.converted(to: .fluidOunces).toString())
            Text(mass.converted(to: .grams).toString())
            Text(temp.converted(to: .celsius).toString())
        }
    }
}

要显示区域设置调整的测量值，只需将.current添加到Locale

extension Formatter{
    static func measurement(unitOptions: MeasurementFormatter.UnitOptions? = .providedUnit, unitStyle: Formatter.UnitStyle = .short, numberStyle: NumberFormatter.Style = .decimal) -> MeasurementFormatter{
        
        let f = MeasurementFormatter()
        f.unitStyle = unitStyle
        
        if let options = unitOptions{ //Make unitOptions optional
            f.unitOptions = options
        }
        
        f.locale = .current //Add locale consideration

        let nf = NumberFormatter()
        nf.numberStyle = numberStyle
        
        f.numberFormatter = nf
        
        return f
    }
}
extension Measurement{
    func toString(unitOptions: MeasurementFormatter.UnitOptions? = .providedUnit, unitStyle: Formatter.UnitStyle = .short, numberStyle: NumberFormatter.Style = .decimal) -> String{
        
        let f = Formatter.measurement(unitOptions: unitOptions, unitStyle: unitStyle, numberStyle: numberStyle)
        return f.string(from: self)
    }
}

然后，当您希望单位按地区调整显示时，只需将unitOptions参数设置为nil

Text(volume.toString(unitOptions: nil)) //Will show locale specific version

您的最后一次尝试很接近。只需将用法更改为.liquid而不是asProvided。

Text("\(Measurement(value: Double(brew.water), unit: UnitVolume.milliliters).formatted(.measurement(width: .abbreviated, usage: .liquid, numberFormatStyle: .number)))")

这将给我的结果是“fl oz”，区域设置为en_US。
请注意，MeasurementFormatUnitUsage<UnitVolume>.liquid仅在iOS 16.0中可用，因此此解决方案不适用于iOS 15。