GuidanceUnitSystem public enum GuidanceUnitSystem Preferred system of measurement for announcements. metric Metric system(meters, km). Declaration Swift case metric US Measurement system used in USA(miles, feet). Declaration Swift case US UK Measurement system used in UK(miles, yards). Declaration Swift case UK © 2022 TomTom N.V.. All rights reserved. (Last updated: 2022-09-23) Generated by jazzy ♪♫ v0.14.2, a Realm project.