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I want to write a Unicode string using hexadecimal values in Swift. I have read the documentation for String and Character so I know that I can use special Unicode characters directly in strings like the following:

var variableString = "Cat‼🐱" // "Cat" + Double Exclamation + cat emoji

But I would like to do it using the Unicode code points. The docs (and this question) show it for characters, but are not very clear about how to do it for strings.

(Note: Although the answer seems obvious to me now, it wasn't obvious at all just a short time ago. I am answering my own question below as a means of learning how to do this and also to help myself understand Unicode terminology and how Swift Characters and Strings work.)

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Character

The Swift syntax for forming a hexadecimal code point is

\u{n}

where n is a hexadecimal number up to 8 digits long. The valid range for a Unicode scalar is U+0 to U+D7FF and U+E000 to U+10FFFF inclusive. (The U+D800 to U+DFFF range is for surrogate pairs, which are not scalars themselves, but are used in UTF-16 for encoding the higher value scalars.)

Examples:

// The following forms are equivalent. They all produce "C". 
let char1: Character = "\u{43}"
let char2: Character = "\u{0043}"
let char3: Character = "\u{00000043}"

// Higher value Unicode scalars are done similarly
let char4: Character = "\u{203C}" // ‼ (DOUBLE EXCLAMATION MARK character)
let char5: Character = "\u{1F431}" // 🐱 (cat emoji)

// Characters can be made up of multiple scalars
let char7: Character = "\u{65}\u{301}" // é = "e" + accent mark
let char8: Character = "\u{65}\u{301}\u{20DD}" // é⃝ = "e" + accent mark + circle

Notes:

String

Strings are composed of characters. See the following examples for some ways to form them using hexadecimal code points.

Examples:

var string1 = "\u{0043}\u{0061}\u{0074}\u{203C}\u{1F431}" // Cat‼🐱

// pass an array of characters to a String initializer
let catCharacters: [Character] = ["\u{0043}", "\u{0061}", "\u{0074}", "\u{203C}", "\u{1F431}"] // ["C", "a", "t", "‼", "🐱"]
let string2 = String(catCharacters) // Cat‼🐱

Converting Hex Values at Runtime

At runtime you can convert hexadecimal or Int values into a Character or String by first converting it to a UnicodeScalar.

Examples:

// hex values
let value0: UInt8  = 0x43     // 67
let value1: UInt16 = 0x203C   // 8252
let value2: UInt32 = 0x1F431  // 128049

// convert hex to UnicodeScalar
let scalar0 = UnicodeScalar(value0)
// make sure that UInt16 and UInt32 form valid Unicode values
guard
    let scalar1 = UnicodeScalar(value1),
    let scalar2 = UnicodeScalar(value2) else {
    return
}

// convert to Character
let character0 = Character(scalar0) // C
let character1 = Character(scalar1) // ‼
let character2 = Character(scalar2) // 🐱

// convert to String
let string0 = String(scalar0) // C
let string1 = String(scalar1) // ‼
let string2 = String(scalar2) // 🐱

// convert hex array to String
let myHexArray = [0x43, 0x61, 0x74, 0x203C, 0x1F431] // an Int array
var myString = ""
for hexValue in myHexArray {
    if let scalar = UnicodeScalar(hexValue) {
        myString.append(Character(scalar))
    }
}
print(myString) // Cat‼🐱

Further reading

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12 Comments

@Suragch I have a unicode character \u{0D85}. How do I get the Int value from it?
@Isuru, I have re-asked and answered your question here: How to convert Unicode Character to Int in Swift
@Suragch Thanks so much for the detailed answer. I actually found how to do it in this answer. But still, good to have a thorough explanation.
@Isuru, Just realize that in the answer you linked to, in the off chance that a Character is composed of more than one scalar, only the first scalar value will be returned. Any others will be ignored. (example: let myChar: Character = "\u{65}\u{301}" // é)
how to combine hexadecimal number up to 8 digits long with \u{xxxx}? Hex number is an dynamic
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3

from your Hex "0x1F52D" to actual Emoji

let c = 0x1F602

next step would possibly getting an Uint32 from your Hex

let intEmoji = UnicodeScalar(c!).value

from this you can do something like 

titleLabel.text = String(UnicodeScalar(intEmoji)!)

here you have a "😂"

it work with range of hexadecimal too 

let emojiRanges = [
            0x1F600...0x1F636,
            0x1F645...0x1F64F,
            0x1F910...0x1F91F,
            0x1F30D...0x1F52D
        ]

        for range in emojiRanges {
            for i in range {
                let c = UnicodeScalar(i)!.value
                data.append(c)
            }
        }

to get multiple UInt32 from your Hex range for exemple

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3 Comments

Please do not post the same answer to multiple questions. If the same information really answers both questions, then one question (usually the newer one) should be closed as a duplicate of the other. You can indicate this by voting to close it as a duplicate or, if you don't have enough reputation for that, raise a flag to indicate that it's a duplicate. Otherwise, be sure you tailor your answer to this question and don't just paste the same answer in multiple places.
Made this Medium Article that explain how it works medium.com/@kamiFR/…
often same response apply to many questions and I support when author does this

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