1. Get all UTF-16 bytes that make up the codepoint, and use either this algorithm or CFStringGetLongCharacterForSurrogatePair to convert the surrogate pairs to UTF-32.
2. Use either dataUsingEncoding: or getBytes:maxLength:usedLength:encoding:options:range:remainingRange: to convert the NSString to UTF-32, and interpret the raw bytes as a uint32_t.
3. Use a library like ICU.

nav a:hover {content:"&darr";}

nav a:hover:after {
    content: "↓";
}

nav a:hover:after {
    content: "\2193";
}

       Third, backslash escapes allow authors to refer to characters they cannot easily put in a document. In this case, the backslash is followed by at most six hexadecimal digits (0..9A..F), which stand for the ISO 10646 ([ISO10646]) character with that number, which must not be zero. (It is undefined in CSS 2.1 what happens if a style sheet does contain a character with Unicode codepoint zero.) If a character in the range [0-9a-fA-F] follows the hexadecimal number, the end of the number needs to be made clear. There are two ways to do that:

1. with a space (or other white space character): "\26 B" ("&B"). In this case, user agents should treat a "CR/LF" pair (U+000D/U+000A) as a single white space character.
2. by providing exactly 6 hexadecimal digits: "\000026B" ("&B")

In fact, these two methods may be combined. Only one white space character is ignored after a hexadecimal escape. Note that this means that a "real" space after the escape sequence must be doubled.

If the number is outside the range allowed by Unicode (e.g., "\110000" is above the maximum 10FFFF allowed in current Unicode), the UA may replace the escape with the "replacement character" (U+FFFD). If the character is to be displayed, the UA should show a visible symbol, such as a "missing character" glyph (cf. 15.2, point 5).

• Note: Backslash escapes are always considered to be part of an identifier or a string (i.e., "\7B" is not punctuation, even though "{" is, and "\32" is allowed at the start of a class name, even though "2" is not).
  The identifier "te\st" is exactly the same identifier as "test".

Answer:

• ▲ - U+25B2 BLACK UP-POINTING TRIANGLE
• ▼ - U+25BC BLACK DOWN-POINTING TRIANGLE
• ▴ - U+25B4 SMALL BLACK UP-POINTING TRIANGLE
• ▾ - U+25BE SMALL BLACK DOWN-POINTING TRIANGLE

• http://en.wikipedia.org/wiki/Arrow_%28symbol%29#Arrows_in_Unicode
• http://en.wikipedia.org/wiki/Geometric_Shapes

• Accuracy
  utf8mb4_unicode_ci is based on the Unicode standard for sorting and comparison, which sorts accurately in a very wide range of languages.
  utf8mb4_general_ci fails to implement all of the Unicode sorting rules, which will result in undesirable sorting in some situations, such as when using particular languages or characters.
• Performance
  utf8mb4_general_ci is faster at comparisons and sorting, because it takes a bunch of performance-related shortcuts.
  On modern servers, this performance boost will be all but negligible. It was devised in a time when servers had a tiny fraction of the CPU performance of today's computers.
  utf8mb4_unicode_ci, which uses the Unicode rules for sorting and comparison, employs a fairly complex algorithm for correct sorting in a wide range of languages and when using a wide range of special characters. These rules need to take into account language-specific conventions; not everybody sorts their characters in what we would call 'alphabetical order'.

• For examples, the Unicode collation sorts "ß" like "ss", and "Œ" like "OE" as people using those characters would normally want, whereas utf8mb4_general_ci sorts them as single characters (presumably like "s" and "e" respectively).
• Some Unicode characters are defined as ignorable, which means they shouldn't count toward the sort order and the comparison should move on to the next character instead.utf8mb4_unicode_ci handles these properly.