unsigned int ipQuads[4];
const char *ipAddress = [ipAddressStr cStringUsingEncoding:NSUTF8StringEncoding];

sscanf(ipAddress, "%u.%u.%u.%u", &ipQuads[0], &ipQuads[1], &ipQuads[2], &ipQuads[3]);

@try {
   for (int quad = 0; quad < 4; quad++) {
      if ((ipQuads[quad] < 0) || (ipQuads[quad] > 255)) {
         NSException *ipException = [NSException
            exceptionWithName:@"IPNotFormattedCorrectly"
            reason:@"IP range is invalid"
            userInfo:nil];
         @throw ipException;
      }
   }
}
@catch (NSException *exc) {
   NSLog(@"ERROR: %@", [exc reason]);
}

#include <arpa/inet.h>

- (BOOL)isIp:(NSString*)string{
    struct in_addr pin;
    int success = inet_aton([string UTF8String],&pin);
    if (success == 1) return TRUE;
    return FALSE;
}