On basis of definition of adler32 checksum as mentioned in wikipedia,
Objective C implementation would be like this:
static NSNumber * adlerChecksumof(NSString *str)
{
NSMutableData *data= [[NSMutableData alloc]init];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
for (int i = 0; i < ([str length] / 2); i++)
{
byte_chars[0] = [str characterAtIndex:i*2];
byte_chars[1] = [str characterAtIndex:i*2+1];
whole_byte = strtol(byte_chars, NULL, 16);
[data appendBytes:&whole_byte length:1];
}
int16_t a=1;
int16_t b=0;
Byte * dataBytes= (Byte *)[data bytes];
for (int i=0; i<[data length]; i++)
{
a+= dataBytes[i];
b+=a;
}
a%= 65521;
b%= 65521;
int32_t adlerChecksum= b*65536+a;
return @(adlerChecksum);
}
Here str
would be your string as mentioned in your question..
So when you want to calculate checksum of some string just do this:
NSNumber * calculatedChkSm= adlerChecksumof(@"1217278743473774374");
Please Let me know if more info needed