How to replace emoji characters with their descriptions in a Swift string

Question

I'm looking for a way to replace emoji characters with their description in a Swift string.

Example:

Input "This is my string 😄"

I'd like to replace the 😄 to get:

Output "This is my string {SMILING FACE WITH OPEN MOUTH AND SMILING EYES}"

To date I'm using this code modified from the original code of this answer by MartinR, but it works only if I deal with a single character.

let myCharacter : Character = "😄"
let cfstr = NSMutableString(string: String(myCharacter)) as CFMutableString
var range = CFRangeMake(0, CFStringGetLength(cfstr))
CFStringTransform(cfstr, &range, kCFStringTransformToUnicodeName, Bool(0))
var newStr = "\(cfstr)"

// removing "\N"  from the result: \N{SMILING FACE WITH OPEN MOUTH AND SMILING EYES}
newStr = newStr.stringByReplacingOccurrencesOfString("\\N", withString:"")

print("\(newStr)") // {SMILING FACE WITH OPEN MOUTH AND SMILING EYES}

How can I achieve this?

Answer 1

Simply do not use a Character in the first place but use a String as input:

let cfstr = NSMutableString(string: "This 😄 is my string 😄") as CFMutableString

that will finally output

This {SMILING FACE WITH OPEN MOUTH AND SMILING EYES} is my string {SMILING FACE WITH OPEN MOUTH AND SMILING EYES}

Put together:

func transformUnicode(input : String) -> String {
    let cfstr = NSMutableString(string: input) as CFMutableString
    var range = CFRangeMake(0, CFStringGetLength(cfstr))
    CFStringTransform(cfstr, &range, kCFStringTransformToUnicodeName, Bool(0))
    let newStr = "\(cfstr)"
    return newStr.stringByReplacingOccurrencesOfString("\\N", withString:"")
}

transformUnicode("This 😄 is my string 😄")

Answer 2

Here is a complete implementation.

It avoids to convert to description also the non-emoji characters (e.g. it avoids to convert “ to {LEFT DOUBLE QUOTATION MARK}). To accomplish this, it uses an extension based on this answer by Arnold that returns true or false whether a string contains an emoji.

The other part of the code is based on this answer by MartinR and the answer and comments to this answer by luk2302.

var str = "Hello World 😄 …" // our string (with an emoji and a horizontal ellipsis)

let newStr = str.characters.reduce("") { // loop through str individual characters
    var item = "\($1)" // string with the current char
    let isEmoji = item.containsEmoji // true or false
    if isEmoji {
        item = item.stringByApplyingTransform(String(kCFStringTransformToUnicodeName), reverse: false)!
    }
    return $0 + item
}.stringByReplacingOccurrencesOfString("\\N", withString:"") // strips "\N"


extension String {
    var containsEmoji: Bool {
        for scalar in unicodeScalars {
            switch scalar.value {
            case 0x1F600...0x1F64F, // Emoticons
            0x1F300...0x1F5FF, // Misc Symbols and Pictographs
            0x1F680...0x1F6FF, // Transport and Map
            0x2600...0x26FF,   // Misc symbols
            0x2700...0x27BF,   // Dingbats
            0xFE00...0xFE0F,   // Variation Selectors
            0x1F900...0x1F9FF:   // Various (e.g. 🤖)
                return true
            default:
                continue
            }
        }
        return false
    }
}

print (newStr) // Hello World {SMILING FACE WITH OPEN MOUTH AND SMILING EYES} …

Please note that some emoji could not be included in the ranges of this code, so you should check if all the emoji are converted at the time you will implement the code.