EnumerateByComposedCharacterSequence

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace TestEmojiEnumeration
{
    class Program
    {
        static void Main(string[] args)
        {
            var text = "ciao 😎👨‍👨‍👦‍👦👨‍👨‍👧‍👧👩‍👩‍👧‍👦 ciao 👩‍👩‍👧👳🏿 ciao";
            foreach (var last in EnumerateByComposedCharacterSequence(text))
            {
                Debug.WriteLine(last);
            }

            Console.ReadLine();
        }

        public static IEnumerable<string> EnumerateByComposedCharacterSequence(string text)
        {
            var last = string.Empty;
            var joiner = true;

            for (int i = 0; i < text.Length; i++)
            {
                if (char.IsSurrogatePair(text, i))
                {
                    // skin modifier for emoji diversity acts as a joiner
                    if (!joiner && !IsSkinModifierCharacter(text, i))
                    {
                        yield return last;
                        last = string.Empty;
                        joiner = true;
                    }

                    last += text[i + 0];
                    last += text[i + 1];
                    joiner = false;
                    i++;
                }
                else if (text[i] == 0x200D) // zero width joiner
                {
                    last += text[i];
                    joiner = true;
                }
                else
                {
                    if (last.Length > 0)
                    {
                        yield return last;
                    }

                    yield return text[i].ToString();
                    last = string.Empty;
                    joiner = true;
                }
            }

            if (last.Length > 0)
            {
                yield return last;
            }
        }

        public static bool IsSkinModifierCharacter(string s, int index)
        {
            if (index + 2 <= s.Length)
            {
                char c1 = s[index + 0];
                char c2 = s[index + 1];
                return c1 == '\ud83c' && c2 >= '\udffb' && c2 <= '\udfff';
            }

            return false;
        }
    }
}