Geek Answers Handbook

Why does Swift treat this Grapheme cluster as two characters instead of one?

In general, Swift really knows how to count graphemes as clusters as a single character. For example, if I want to make a Lebanese flag, I can combine two Unicode characters

  • U + 1F1F1 LETTER OF THE SIGNAL OF THE REGIONAL INDICATOR L
  • U + 1F1E7 SAMPLE SYMBOLS REGIONAL INDICATOR B

and, as expected, this is one character in Swift:

let s = "\u{1f1f1}\u{1f1e7}"
assert(s.characters.count == 1)
assert(s.utf16.count == 4)
assert(s.utf8.count == 8)

However, let me say that I want to make a Bicyclist emoji from Fitzpatrick Type-5. If i combine

  • U + 1F6B4 BICYCLIST
  • U + 1F3FE EMOJI MODIFIER FITZPATRICK TYPE-5

Swift considers this combination to be two characters!

let s = "\u{1f6b4}\u{1f3fe}"
assert(s.characters.count == 2)   // <----- WHY?
assert(s.utf16.count == 4)
assert(s.utf8.count == 8)

Why are these two characters instead of one?

To show why I expect this to be 1, note that this cluster is actually interpreted as a valid emoji:

enter image description here

+4
1

, emrys57. Unicode "" Swift, , Grapheme, UAX # 29 Unicode Text Segmentation. , Emoji . , UAX # 29, "\u{1f6b4}\u{1f3fe}" grapheme. . Ken Whistler Unicode :

- , , . [...] , - UAX # 29 .

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