Credit Card Type Parsing for Swift
CardParser is a lightweight utility for identifying major credit card types from in-progress input. This is useful for building responsive credit entry forms and validating input.
For now, just download and add CardParser.swift to your project.
To determine the state of some in-progress text:
switch CardState(fromPrefix: cardString) { case .identified(let card): //do something with card case .indeterminate(let possibleCards): //do something with possibleCards case .invalid: //show some validation error }
Or if you are just concerned with the validity of some completed input:
guard CardState(fromNumber: cardNumber) != .invalid else { //show some validation error }
CardParser.swift contains the enums:
CardTypeCardState
CardType encapsulates credit card issuers and their validation/ formatting requirements
enum CardType { case amex case diners case discover case jcb case masterCard case visa }
You can interact with an extracted card type to update your form:
let visa: CardType = .visa visa.isPrefixValid("4") //true visa.isValid("4") //false visa.cvvLength //3 visa.segmentGroupings //[4, 4, 4, 4] visa.maxLength //19
CardState can be leveraged to identify the CardType (or possible CardTypes) of some input.
enum CardState { case identified(CardType) case indeterminate([CardType]) case invalid }
Use CardState to extract state and type information
CardState(fromPrefix: "4") //.identified(.visa) CardState(fromPrefix: "3") //.indeterminate([.amex, .diners, .jcb]) CardState(fromPrefix: "0") //.invalid
For example, you may write a method to return a card image for your form:
func cardImage(forState cardState:CardState) -> UIImage? { switch cardState { case .identified(let cardType): switch cardType{ case .visa: return #imageLiteral(resourceName: "credit_cards_visa") case .masterCard: return #imageLiteral(resourceName: "credit_cards_mastercard") case .amex: return #imageLiteral(resourceName: "credit_cards_americanexpress") case .diners: return #imageLiteral(resourceName: "credit_cards_diners") case .discover: return #imageLiteral(resourceName: "credit_cards_discover") case .jcb: return #imageLiteral(resourceName: "credit_cards_jcb") } case .indeterminate: return #imageLiteral(resourceName: "credit_cards_generic") case .invalid: return #imageLiteral(resourceName: "credit_cards_invalid") } }
Jay Clark: jason.clark@raizlabs.com
CardParser is available under the MIT license. See the LICENSE file for more info.