search for mention with dots in the middle

regex.playground

content//: Playground - noun: a place where people can play

import UIKit
import Foundation

var str = "Hello, @playground.something more"
//(?<=\\s|^|\\b)(?:[-'.%$#&/]\\b|\\b[-'.%$#&/]|[A-Za-z0-9]|\\([A-Za-z0-9]+\\))+(?=\\s|$|\\b)
let range = NSMakeRange(0, str.characters.count)

var regex = try! NSRegularExpression(pattern: "@(?<=\\s|^|\\b)(?:[-'.%$#&/]\\b|\\b[-'.%$#&/]|[A-Za-z0-9]|\\([A-Za-z0-9]+\\))+(?=\\s|$|\\b)", options: .caseInsensitive)

regex.stringByReplacingMatches(in: str, options: [], range: range, withTemplate: "Found ya!")