Enable custom detectors with MessageKit

detectors.swift

extension MyAwesomeViewController: MessagesDisplayDelegate {
  
    // ...

    func enabledDetectors(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> [DetectorType] {
        return [.hashtag, .custom(try! NSRegularExpression(pattern: "@[a-zA-Z0-9]{4,}", options: [])) ]
    }
  
    // ...

}