Let’s break down why your current decode method isn’t working and get those emojis showing up properly.

The Root Problem #

Your existing decodeEmoji() method is designed to reverse the encodeEmoji() process, which converts actual emoji characters into a non-lossy ASCII representation (stored as UTF-8). But the string you’re working with is already a UTF-8 string containing raw Unicode escape sequences (like \u2705 or \uD83D\uDE02), not the output of encodeEmoji(). That’s why decoding it with your current method leaves it unchanged—there’s no non-lossy ASCII data to convert back.

The Solution: Parse Unicode Escape Sequences #

We need a custom method that scans the string for \u escape codes and converts them into their corresponding emoji/Unicode characters. Here’s an updated String extension that handles this scenario, plus keeps your original encode/decode for valid use cases:

extension String {
    // Decodes Unicode escape sequences (\uXXXX) into actual characters
    func decodeUnicodeEscapes() -> String {
        let scanner = Scanner(string: self)
        var result = ""
        var tempString: NSString?
        
        while !scanner.isAtEnd {
            // Read all characters until we hit a \u escape
            if scanner.scanUpTo("\\u", into: &tempString), let part = tempString as String? {
                result += part
            }
            
            guard !scanner.isAtEnd else { break }
            
            // Skip the "\u" prefix
            scanner.scanString("\\u", into: nil)
            
            // Read the 4-digit hexadecimal code
            var hexCode: NSString?
            if scanner.scanCharacters(from: .hexadecimal, into: &hexCode), 
               let hex = hexCode as String?, 
               hex.count == 4,
               let code = UInt32(hex, radix: 16),
               let scalar = UnicodeScalar(code) {
                // Convert hex to Unicode scalar and append to result
                result.append(Character(scalar))
            } else {
                // If parsing fails, add the \u back to avoid data loss
                result += "\\u"
                if let invalidHex = hexCode as String? {
                    result += invalidHex
                }
            }
        }
        
        return result
    }
    
    // Original encode method (for converting actual emojis to ASCII-safe escapes)
    func encodeEmojiToASCII() -> String {
        guard let data = self.data(using: .nonLossyASCII, allowLossyConversion: true) else {
            return self
        }
        return String(data: data, encoding: .utf8) ?? self
    }
    
    // Original decode method (for reversing encodeEmojiToASCII)
    func decodeEmojiFromASCII() -> String? {
        guard let data = self.data(using: .utf8) else {
            return nil
        }
        return String(data: data, encoding: .nonLossyASCII)
    }
}

How to Use It #

For your specific string, call the new decodeUnicodeEscapes() method instead:

let encodedResponse = "I love too...\n\u2705 Laugh \uD83D\uDE02\n\u2705 Read novels \uD83D\uDCDA\n\u2705 Watch movies \uD83C\uDFAC\n\u2705 Go for bike rides \uD83D\uDEB5\uD83C\uDFFD\u200D\u2640\uFE0F\n\u2705 Go for long walks \uD83D\uDEB6\uD83C\uDFFD\u200D\u2640\uFE0F\n\u2705 Cook \uD83D\uDC69\uD83C\uDFFD\u200D\uD83C\uDF73\n\u2705 Travel \uD83C\uDDEA\uD83C\uDDFA\uD83C\uDDEE\uD83C\uDDF3\uD83C\uDDEC\uD83C\uDDE7\n\u2705 Eat \uD83C\uDF2E\uD83C\uDF5F\uD83C\uDF73\n\u2705 Play board games \u265F\n\u2705 Go to the theatre \uD83C\uDFAD\nMy favourite season is autumn \uD83C\uDF42, i love superhero movies \uD83E\uDDB8\u200D\u2642\uFE0F and Christmas is the most wonderful time of the year! \uD83C\uDF84"

let decodedAboutMe = encodedResponse.decodeUnicodeEscapes()
print(decodedAboutMe)

This will output the string with all emojis rendered correctly, like:

I love too...
✅ Laugh 😂
✅ Read novels 📚
✅ Watch movies 🎬
...and so on

When to Use the Original Methods #

Keep encodeEmojiToASCII() and decodeEmojiFromASCII() for cases where you need to convert actual emoji characters into an ASCII-safe format (e.g., storing in a database or sending via an API that doesn’t support raw emojis). For example:

let emojiString = "I love 😂 and 🎬!"
let asciiSafe = emojiString.encodeEmojiToASCII() // "I love \uD83D\uDE02 and \uD83C\uDFAC!"
let decodedBack = asciiSafe.decodeEmojiFromASCII() // "I love 😂 and 🎬!"

内容的提问来源于stack exchange，提问作者Tushar Amkar