ios - Choosing units with MeasurementFormatter

Question

This is similar to a question I asked yesterday but the answer I got doesn't seem to work in this case.

I'm getting altitude values in meters from Core Location. I want to display these in a localized form. As an example, the altitude where I am right now is 1839m above sea level. This should be displayed as 6033 feet. The best I can do with MeasurementFormatter is "1.143 mi".

let meters : Double = 1839
let metersMeasurement = Measurement(value: meters, unit: UnitLength.meters)

let measurementFormatter = MeasurementFormatter()
measurementFormatter.locale = Locale(identifier: "en_US")

let localizedString = measurementFormatter.string(from: metersMeasurement)

The .naturalScale option that answered my previous question doesn't help here. I think this is a limitation of the framework, but I wonder if anyone has a workaround for now.

Answer 1

You just need to convert your UnitLength from meters to feet. You can also create a custom US measurement formatter to display it as needed:

extension Measurement where UnitType == UnitLength {
    private static let usFormatted: MeasurementFormatter = {
       let formatter = MeasurementFormatter()
        formatter.locale = Locale(identifier: "en_US")
        formatter.unitOptions = .providedUnit
        formatter.numberFormatter.maximumFractionDigits = 0
        formatter.unitStyle = .long
        return formatter
    }()
    var usFormatted: String { Measurement.usFormatted.string(from: self) }
}

---

Playground

let value: Double = 1839
let meters: Measurement<UnitLength> = .init(value: value, unit: .meters)
let feet = meters.converted(to: .feet)
let formatted = feet.usFormatted
print(formatted)    // "6,033 feet"