Unescape HTML special characters of String in Swift

unescape.swift

func convertSpecialCharacters(string: String) -> String {
    var newString = string
    var char_dictionary = [
        "&": "&",
        "&lt;": "<",
        "&gt;": ">",
        "&quot;": "\"",
        "&apos;": "'"
    ];
    for (escaped_char, unescaped_char) in char_dictionary {
        newString = newString.stringByReplacingOccurrencesOfString(escaped_char, withString: unescaped_char, options: NSStringCompareOptions.RegularExpressionSearch, range: nil)
    }
    return newString
}

With an extension:

extension String {
    func unescape() -> String {
        let characters = [
            "&": "&",
            "&lt;": "<",
            "&gt;": ">",
            "&quot;": "\"",
            "&apos;": "'"
        ]
        var str = self
        for (escaped, unescaped) in characters {
            str = str.replacingOccurrences(of: escaped, with: unescaped, options: NSString.CompareOptions.literal, range: nil)
        }
        return str
    }
}