Swift Character-is-emoji checker

Character+isEmoji.swift

import Foundation

extension Character {
    /// An approximation of a spec-compatible "is this an emoji" check for the character.
    /// Will recognize standard, flag, composite, tag emoji, and keycap emoji.
    /// Unfortunately, will return true for "text presented" and malformed emoji too,
    /// because I didn't do the whole CFG from Unicode.
    var isEmoji: Bool {
        // Empty character returns false
        guard let first = self.unicodeScalars.first else {
            return false
        }

        // 0-9, #, and * can be turned into emoji with the "emoji presentation" suffix
        if first == "#" || first == "*" || (first >= "0" && first <= "9") {
            let rest = self.unicodeScalars.dropFirst()
            let emojiPresentationSuffix = [Unicode.Scalar(UInt32(0xFE0F))!, Unicode.Scalar(UInt32(0x20E3))!]
            return rest.starts(with: emojiPresentationSuffix)
        }

        // All other emoji
        return first.properties.isEmojiModifierBase || first.properties.isEmojiPresentation
    }
}