bitwarden-mobile/src/App/Models/PlatformCulture.cs

using System;

namespace Bit.App.Models
{
    public class PlatformCulture
    {
        public PlatformCulture(string platformCultureString)
        {
            if(string.IsNullOrWhiteSpace(platformCultureString))
            {
                throw new ArgumentException("Expected culture identifier.", nameof(platformCultureString));
            }

            // .NET expects dash, not underscore
            PlatformString = platformCultureString.Replace("_", "-");
            var dashIndex = PlatformString.IndexOf("-", StringComparison.Ordinal);
            if(dashIndex > 0)
            {
                var parts = PlatformString.Split('-');
                LanguageCode = parts[0];
                LocaleCode = parts[1];
            }
            else
            {
                LanguageCode = PlatformString;
                LocaleCode = string.Empty;
            }
        }

        public string PlatformString { get; private set; }
        public string LanguageCode { get; private set; }
        public string LocaleCode { get; private set; }

        public override string ToString()
        {
            return PlatformString;
        }
    }
}