EmojiFlag.swift

extension String {
    private func regionalIndicatorSymbol(unicodeScalar: UnicodeScalar) -> UnicodeScalar? {
        let uppercaseA = UnicodeScalar("A")!
        let regionalIndicatorSymbolA = UnicodeScalar("\u{1f1e6}")!
        let distance = unicodeScalar.value - uppercaseA.value
        return UnicodeScalar(regionalIndicatorSymbolA.value + distance)
    }
    
    public var emojiFlag: String {
        return self.uppercased().unicodeScalars.map({
            String(regionalIndicatorSymbol(unicodeScalar: $0)!)
        }).joined()
    }
}

"IR".emojiFlag