DebitCard - Auto detect card type. Supported Cards: American Express, Discover, MasterCard, Visa Card

LKDebitCard.h

//
//  LKDebitCard.m
//  DebitCard
//
//  Created by LK on 21/12/17.
//  Copyright © 2017 LK. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSString (Luhn_Private)

- (NSString *) formattedStringForProcessing;

@end

typedef NS_ENUM(NSInteger, PaymentMethod) {
    PaymentMethodNotSet,
    PaymentMethodPaypal,
    PaymentMethodDebitCard,
};

typedef NS_ENUM(NSUInteger, CardType) {
    CardTypeInvalid,
    CardTypeUnsupported,
    CardTypeAmericanExpress,
    CardTypeDiscover,
    CardTypeMasterCard,
    CardTypeVisa,
    
};

static NSUInteger const MaxZipLength = 5;

@interface LKDebitCard : NSObject

@property (assign, nonatomic) CardType type;

@property (strong, nonatomic) NSString *strNumber;

@property (strong, nonatomic) NSString *strExpireOn;

@property (strong, nonatomic) NSString *strCVV;

@property (strong, nonatomic) NSString *strZip;

@property (assign, nonatomic, readonly, getter=isValid) BOOL valid;

- (UIImage *)icon;
- (UIImage *)iconFilled:(BOOL)filled;

- (void)findCardType;

- (BOOL)minLengthReached;
- (BOOL)isMaxed;

- (BOOL)appendCardNumber:(NSString *)number;
- (BOOL)deleteLastCardNumber;

- (BOOL)appendExpiry:(NSString *)number;
- (BOOL)deleteExpiryLastDigit;

- (BOOL)appendCVV:(NSString *)number;
- (BOOL)deleteLastCVVDigit;

- (BOOL)appendZIP:(NSString *)number;
- (BOOL)deleteLastZIPDigit;

- (NSUInteger)maxLengthCVV;

- (BOOL)isValidCardNumber;
- (BOOL)isValidExpiry;
- (BOOL)isValidCVV;
- (BOOL)isValidZip;

- (BOOL)isValidCardDetails;

@end

LKDebitCard.m

//
//  LKDebitCard.m
//  DebitCard
//
//  Created by LK on 21/12/17.
//  Copyright © 2017 LK. All rights reserved.
//

#import "LKDebitCard.h"

@implementation NSString (Luhn_Private)

- (NSString *) formattedStringForProcessing {
    NSCharacterSet *illegalCharacters = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    NSArray *components = [self componentsSeparatedByCharactersInSet:illegalCharacters];
    return [components componentsJoinedByString:@""];
}

@end

@implementation LKDebitCard

@synthesize valid = _valid;

- (instancetype)init {
    self = [super init];
    if (self) {
        self.strNumber = @"";
    }
    return self;
}


- (instancetype)copyWithZone:(NSZone *)zone {
    LKDebitCard *card = [LKDebitCard new];
    if (card) {
        card.type = self.type;
        card.strNumber = [self.strNumber copyWithZone:zone];
        self.strExpireOn = [self.strExpireOn copyWithZone:zone];
        self.strCVV = [self.strCVV copyWithZone:zone];
        self.strZip = [self.strZip copyWithZone:zone];
    }
    return card;
}

#pragma mark - Getter

- (BOOL)isValid {
    return [self validateString:self.strNumber];
}

#pragma mark - Valid

- (BOOL)isValidCardNumber {
    return !(!self.isValid || self.type == CardTypeInvalid || self.type == CardTypeUnsupported);
}

- (BOOL)isValidExpiry {
    return self.strExpireOn.length >= 5;
}

- (BOOL)isValidCVV {
    return self.strCVV.length == [self maxLengthCVV];
}

- (BOOL)isValidZip {
    return self.strZip.length >= MaxZipLength;
}

- (BOOL)isValidCardDetails {
    return [self isValidCardNumber] && [self isValidExpiry] && [self isValidCVV] && [self isValidZip];
}

#pragma mark -
#pragma mark - Public Methods

- (UIImage *)icon {
    return [self iconFilled:NO];
}
- (UIImage *)iconFilled:(BOOL)filled {
    if (self.type == CardTypeInvalid || self.type == CardTypeUnsupported) {
        return nil;
    }
    
    NSString *imageName;
    switch (_type) {
        case CardTypeAmericanExpress:
            imageName = @"amex";
            break;
            
        case CardTypeDiscover:
            imageName = @"discover";
            break;
            
        case CardTypeMasterCard:
            imageName = @"mastercard";
            break;
            
        case CardTypeVisa:
            imageName = @"visa";
            break;
            
        default:
            break;
    }
    if (filled) {
        imageName = [NSString stringWithFormat:@"%@Fill", imageName];
    }
    UIImage *icon = [UIImage imageNamed:imageName];
    return icon;
}

- (void)findCardType {
    CardType type = [self typeFromString:self.strNumber];
    self.type = type;
}

#pragma mark - Expiry

- (BOOL)appendExpiry:(NSString *)number {
    NSString *expiry = self.strExpireOn ?: @"";
    
    NSMutableString *mutableString = [NSMutableString stringWithString:expiry];
    
    if (mutableString.length == 0 && [number integerValue] > 1) {
        [mutableString appendString:@"0"];
    }
    
    if (mutableString.length == 2) {
        [mutableString appendString:@"/"];
    }
    
    [mutableString appendString:number];
    
    if (mutableString.length == 2 && [mutableString integerValue] > 12) {
        return false;
    }

    if (mutableString.length > 5) {
        return false;
    }
    
    self.strExpireOn = mutableString;
    return true;
    
}

- (BOOL)deleteExpiryLastDigit {
    if (self.strExpireOn.length < 1) {
//        self.strExpireOn = nil;
        return NO;
    }
    
    if (self.strExpireOn.length > 1) {
        unichar secondLastChar = [self.strExpireOn characterAtIndex:[self.strExpireOn length] - 2];
        if (secondLastChar == '/') {
            self.strExpireOn = [self.strExpireOn substringToIndex:[self.strExpireOn length] - 2];
            return YES;
        }
    }
    self.strExpireOn = [self.strExpireOn substringToIndex:[self.strExpireOn length] - 1];
    return YES;
}

#pragma mark - CVV

- (BOOL)appendCVV:(NSString *)number {
    NSString *cvv = self.strCVV ?: @"";
    cvv = [NSString stringWithFormat:@"%@%@", cvv, number];
    
    if (cvv.length > [self maxLengthCVV]) {
        return false;
    }
    self.strCVV = cvv;
    return true;
}

- (BOOL)deleteLastCVVDigit {
    self.strCVV = [self deleteLastDigit:self.strCVV];
    return true;
}

- (NSUInteger)maxLengthCVV {
    NSUInteger maxLength = (self.type == CardTypeAmericanExpress) ? 4 : 3;
    return maxLength;
}

#pragma mark - ZIP

- (BOOL)appendZIP:(NSString *)number {
    NSString *zip = self.strZip ?: @"";
    zip = [NSString stringWithFormat:@"%@%@", zip, number];
    
    if (zip.length > MaxZipLength) {
        return false;
    }
    self.strZip = zip;
    return true;
}

- (BOOL)deleteLastZIPDigit {
    self.strZip = [self deleteLastDigit:self.strZip];
    return true;
}

#pragma mark - Common

- (NSString *)deleteLastDigit:(NSString *)string {
    if (string.length < 1) {
        return @"";
    }
    string = [string substringToIndex:[string length] - 1];
    return string;
}

#pragma mark - Card Number

- (BOOL)appendCardNumber:(NSString *)number {
    if (!number) {
        return NO;
    }
    NSString *text = self.strNumber;
    
    NSMutableString *mutableString = [NSMutableString stringWithString:text];
    
    if (text.length < 4) {
        [mutableString appendString:number];
    }
    
    if (mutableString.length == 4 ) {
        // Time to detect card type
        CardType type = [self typeFromString:mutableString];
        NSLog(@"Card Type Detected: %zd", type);
        self.type = type;
    }
    
    NSUInteger maxLength = [self maximumCardLength];
    if (mutableString.length >= maxLength) {
        return NO;
    }
    
    if (text.length >= 4) {
        if (self.type == CardTypeAmericanExpress) {
            if (text.length == 4 || text.length == 11) {
                [mutableString appendString:@" "];
            }
        } else {
            if (text.length == 4 ||text.length == 9 || text.length == 14 || text.length == 19 ) {
                [mutableString appendString:@" "];
            }
        }
        [mutableString appendString:number];
    }
    self.strNumber = mutableString;
    return YES;
}

- (BOOL)deleteLastCardNumber {
    if (self.strNumber.length < 1) {
        return NO;
    }
    
    if (self.strNumber.length > 1) {
        unichar secondLastChar = [self.strNumber characterAtIndex:[self.strNumber length] - 2];
        if (secondLastChar == ' ') {
            self.strNumber = [self.strNumber substringToIndex:[self.strNumber length] - 2];
            return YES;
        }
    }
    self.strNumber = [self.strNumber substringToIndex:[self.strNumber length] - 1];
    return YES;
}

- (BOOL)isMaxed {
    NSUInteger maxLength = [self maximumCardLength];
    if (self.strNumber.length >= maxLength) {
        return YES;
    }
    return NO;
}

- (NSUInteger)maximumCardLength {
    return [self maxLengthForCardType:self.type];
}

- (NSUInteger) maxLengthForCardType:(CardType)type {
    switch (type) {
        case CardTypeAmericanExpress:
            return 15 + 2;
            break;
            
        case CardTypeDiscover:
            return 19 + 4;
            break;
            
        case CardTypeMasterCard:
            return 16 + 3;
            break;
            
        case CardTypeVisa:
            return 19 + 4;
            break;
            
        default:
            break;
    }
    return 16 + 3;
}

- (BOOL)minLengthReached {
    NSUInteger minLength = [self minLengthForCardType:self.type];
    if (self.strNumber.length >= minLength) {
        return YES;
    }
    return NO;
}

- (NSUInteger) minLengthForCardType:(CardType)type {
    switch (type) {
        case CardTypeAmericanExpress:
            return 15 + 2;
            break;
            
        case CardTypeDiscover:
            return 16 + 3;
            break;
            
        case CardTypeMasterCard:
            return 16 + 3;
            break;
            
        case CardTypeVisa:
            return 13 + 3;
            break;
            
        default:
            break;
    }
    return 13 + 3;
}

#pragma mark - Private Methods

- (BOOL)validateString:(NSString *)string {
    NSString *formattedString = [string formattedStringForProcessing];
    if (formattedString == nil || formattedString.length < 9 || ![self minLengthReached]) {
        return NO;
    }
    NSMutableString *reversedString = [NSMutableString stringWithCapacity:[formattedString length]];
    
    [formattedString enumerateSubstringsInRange:NSMakeRange(0, [formattedString length]) options:(NSStringEnumerationReverse |NSStringEnumerationByComposedCharacterSequences) usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
        [reversedString appendString:substring];
    }];
    
    NSUInteger oddSum = 0, evenSum = 0;
    
    for (NSUInteger i = 0; i < [reversedString length]; i++) {
        NSInteger digit = [[NSString stringWithFormat:@"%C", [reversedString characterAtIndex:i]] integerValue];
        
        if (i % 2 == 0) {
            evenSum += digit;
        }
        else {
            oddSum += digit / 5 + (2 * digit) % 10;
        }
    }
    return (oddSum + evenSum) % 10 == 0;
}

- (CardType) typeFromString:(NSString *) string {
    
    NSString *formattedString = [string formattedStringForProcessing];
    if (formattedString == nil || formattedString.length < 4) {
        return CardTypeInvalid;
    }
    
    NSArray<NSNumber *> *enums = @[ @(CardTypeAmericanExpress), @(CardTypeDiscover), @(CardTypeMasterCard), @(CardTypeVisa) ];
    
    __block CardType type = CardTypeInvalid;
    [enums enumerateObjectsUsingBlock:^(NSNumber * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        CardType _type = [obj integerValue];
        NSPredicate *predicate = [LKDebitCard predicateForType:_type];
        BOOL isCurrentType = [predicate evaluateWithObject:formattedString];
        if (isCurrentType) {
            type = _type;
            *stop = YES;
        }
    }];
    return type;
}

+ (NSPredicate *) predicateForType:(CardType) type {
    if (type == CardTypeInvalid || type == CardTypeUnsupported) {
        return nil;
    }
    NSString *regex = nil;
    switch (type) {
        case CardTypeAmericanExpress:
            regex = @"^3[47][0-9]{0,}$"; //^3[47][0-9]{5,}$
            break;
        case CardTypeDiscover:
            regex = @"^(6011|65|64[4-9]|62212[6-9]|6221[3-9]|622[2-8]|6229[01]|62292[0-5])[0-9]{0,}$"; //^6(?:011|5[0-9]{2})[0-9]{3,}$
            break;
        case CardTypeMasterCard:
            regex = @"^(5[1-5]|222[1-9]|22[3-9]|2[3-6]|27[01]|2720)[0-9]{0,}$"; //^5[1-5][0-9]{5,}|222[1-9][0-9]{3,}|22[3-9][0-9]{4,}|2[3-6][0-9]{5,}|27[01][0-9]{4,}|2720[0-9]{3,}$
            break;
        case CardTypeVisa:
            regex = @"^4[0-9]{0,}$";//^4[0-9]{6,}$
            break;
        default:
            break;
    }
    return [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
}

@end