temperature.swift

extension Locale {
    var defaultTemperatureUnit: UnitTemperature {
        if #available(iOS 16, *) {
            return UnitTemperature(forLocale: self, usage: .general)
        } else {
            let mCel = Measurement(value: 0, unit: UnitTemperature.celsius)
            let f = MeasurementFormatter()
            f.locale = self

            let s1 = f.string(from: mCel)

            f.unitOptions = .providedUnit
            let s2 = f.string(from: mCel)

            return s1 == s2 ? .celsius : .fahrenheit
        }
    }
}