uic-918-3 aztec barcode decoding ios objective-c

uic9183aztecbarcodedecoding.m

// add this method to ZXAztecDecoder.m (ZXingObjC)

+ (NSString *)UIC9183TicketId:(ZXBoolArray *)correctedBits
{
    NSMutableData *bytes = [[NSMutableData alloc] init];
    
    int endIndex = (int)correctedBits.length;
    ZXAztecTable latchTable = ZXAztecTableUpper; // table most recently latched to
    ZXAztecTable shiftTable = ZXAztecTableUpper; // table to use for the next read
 
    int index = 0;
    int byteIndex = 0;
    
    while (index < endIndex) {
        if (shiftTable == ZXAztecTableBinary) {
            if (endIndex - index < 5) {
                break;
            }
            int length = [self readCode:correctedBits startIndex:index length:5];
            index += 5;
            if (length == 0) {
                if (endIndex - index < 11) {
                    break;
                }
                
                length = [self readCode:correctedBits startIndex:index length:11] + 31;
                index += 11;
            }
            for (int charCount = 0; charCount < length; charCount++) {
                if (endIndex - index < 8) {
                    index = endIndex;  // Force outer loop to exit
                    break;
                }
                
                int code = [self readCode:correctedBits startIndex:index length:8];
                
                // deflated content starts from byte 68 according to UIC-918-3
                if (byteIndex >= 68) {
                    unsigned char compressedBytes[1];
                    compressedBytes[0] = (unsigned char)code;
                    [bytes appendBytes:compressedBytes length:1];
                }
                
                index += 8;
                byteIndex++;
            }
            // Go back to whatever mode we had been in
            shiftTable = latchTable;
        } else {
            int size = shiftTable == ZXAztecTableDigit ? 4 : 5;
            if (endIndex - index < size) {
                break;
            }
            int code = [self readCode:correctedBits startIndex:index length:size];
            index += size;
            NSString *str = [self character:shiftTable code:code];
            if ([str hasPrefix:@"CTRL_"]) {
                // Table changes
                shiftTable = [self table:[str characterAtIndex:5]];
                if ([str characterAtIndex:6] == 'L') {
                    latchTable = shiftTable;
                }
            } else {
                byteIndex++;
                
                // Go back to whatever mode we had been in
                shiftTable = latchTable;
            }
        }
    }
   
    NSData *inflated1 = [[bytes copy] inflateWithMissingHeader:YES];
    NSData *inflated2 = [[bytes copy] inflateWithMissingHeader:NO];
    
    NSString *inflatedString;
    NSMutableString *ticketID = [[NSMutableString alloc] init];
    
    if (inflated1.length > 0) {
        inflatedString = [[NSString alloc] initWithData:inflated1 encoding:NSUTF8StringEncoding];
    } else if (inflated2.length > 0) {
        inflatedString = [[NSString alloc] initWithData:inflated2 encoding:NSUTF8StringEncoding];
    }
    
    // we find the UIC-918-3 ticket id in the inflated content from 16 to 35
    // it will always be 20 bytes long, so we need to eliminate null-characters and whatnot
    if (inflatedString.length > 36) {
        NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"\\w+"
                                                                               options:0
                                                                                 error:nil];
        NSRange textRange = NSMakeRange(16, 20);
        NSRange matchRange = [regex rangeOfFirstMatchInString:inflatedString
                                                      options:NSMatchingReportProgress
                                                        range:textRange];
        
        if (matchRange.location != NSNotFound) {
            [ticketID appendString:[inflatedString substringWithRange:matchRange]];
        }
    }
    
    return [ticketID copy];
}

// inflating (NSData category)
- (NSData *)inflateWithMissingHeader:(BOOL)missingHeader
{
    if ([self length] == 0) return self;
    
    NSInteger full_length = [self length];
    NSInteger half_length = [self length] / 2;
    
    NSMutableData *decompressed = [NSMutableData dataWithLength: full_length + half_length];
    BOOL done = NO;
    int status;
    
    z_stream strm;
    strm.next_in = (Bytef *)[self bytes];
    strm.avail_in = (unsigned int)[self length];
    strm.total_out = 0;
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    
    if (missingHeader) {
        if (inflateInit2(&strm, -15) != Z_OK) return nil;
    } else {
        if (inflateInit2(&strm, (15+32)) != Z_OK) return nil;
    }
    
    while (!done)
    {
        // Make sure we have enough room and reset the lengths.
        if (strm.total_out >= [decompressed length])
            [decompressed increaseLengthBy: half_length];
        strm.next_out = [decompressed mutableBytes] + strm.total_out;
        strm.avail_out = (unsigned int)([decompressed length] - strm.total_out);
        
        // Inflate another chunk.
        status = inflate (&strm, Z_SYNC_FLUSH);
        if (status == Z_STREAM_END) done = YES;
        else if (status != Z_OK) break;
    }
    if (inflateEnd (&strm) != Z_OK) return nil;
    
    // Set real length.
    if (done)
    {
        [decompressed setLength: strm.total_out];
        return [NSData dataWithData: decompressed];
    }
    else return nil;

}