Determine user's "Temperature Unit" setting on iOS 10 (Celsius / Fahrenheit)

Question

iOS 10 adds the ability for the user to set their "Temperature Unit" choice under Settings > General > Language & Region > Temperature Unit.

How can my app programmatically determine this setting so it can display the right temperature unit? I poured through NSLocale.h and didn't see anything relevant.

(Before iOS 10, it was sufficient to test if the locale used metric and assume that metric users want to use Celsius. This is no longer the case.)

Answer 1

I wrote a little extension for UnitTemperature to get the unit selected based on the findings from Fábio Oliveira. My use case was knowing which unit the user had selected, not necessarily using it to display something, this is how I did it.

extension UnitTemperature {
  static var current: UnitTemperature {
    let measureFormatter = MeasurementFormatter()
    let measurement = Measurement(value: 0, unit: UnitTemperature.celsius)
    let output = measureFormatter.string(from: measurement)
    return output == "0°C" ? .celsius : .fahrenheit
  }
}

Again, remember to test this using an actual device, not a Simulator.