Validate UK Postcodes in Swift 2.0

UKPostcodeValidator.swift

//
//  UKPostcodeValidator.swift
//  Medio
//
//  Created by Daniel Tavares on 20/03/2016.
//  Copyright © 2016 Daniel Tavares. All rights reserved.
//  References: http://stackoverflow.com/questions/164979/uk-postcode-regex-comprehensive
//  References: http://benscheirman.com/2014/06/regex-in-swift/
//  Usage: UKPostcodeValidator.validate("W1D 5LH")
//

import Foundation

private class Regex {
  let internalExpression: NSRegularExpression
  let pattern: String
  
  init(_ pattern: String) {
    self.pattern = pattern
    self.internalExpression = try! NSRegularExpression(pattern: pattern, options: .CaseInsensitive)
  }
  
  func test(input: String) -> Bool {
    let matches = self.internalExpression.matchesInString(input, options: NSMatchingOptions.Anchored, range: NSMakeRange(0, input.characters.count))
    return matches.count > 0
  }
}

struct UKPostcodeValidator {
  static let pattern = "^(GIR 0AA)|((([A-Z][0-9]{1,2})|(([A-Z][A-HJ-Y][0-9]{1,2})|(([A-Z][0-9][A-Z])|([A-Z][A-HJ-Y][0-9]?[A-Z])))) [0-9][A-Z]{2})$"
  static func validate(input: String) -> Bool {
    return Regex(pattern).test(input)
  }
}

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