public extension String { func removing05PrefixIfNeeded() -> String { var result = self if result.count == 66 && result.hasPrefix("05") { result.removeFirst(2) } return result } } @objc public extension NSString { @objc func removing05PrefixIfNeeded() -> NSString { var result = self as String if result.count == 66 && result.hasPrefix("05") { result.removeFirst(2) } return result as NSString } }