How to validate an IP address with regular expression in Objective-C? - objective-c

Question

How to validate an IP address in Objective-C?

Answer 1

Here's a category using the modern inet_pton which will return YES for a valid IPv4 or IPv6 string.
#include <arpa/inet.h>
#implementation NSString (IPValidation)
- (BOOL)isValidIPAddress
{
const char *utf8 = [self UTF8String];
int success;
struct in_addr dst;
success = inet_pton(AF_INET, utf8, &dst);
if (success != 1) {
struct in6_addr dst6;
success = inet_pton(AF_INET6, utf8, &dst6);
}
return success == 1;
}
#end

Answer 2

Here's an alternative approach that might also help. Let's assume you have an NSString* that contains your IP address, called ipAddressStr, of the format a.b.c.d:
int ipQuads[4];
const char *ipAddress = [ipAddressStr cStringUsingEncoding:NSUTF8StringEncoding];
sscanf(ipAddress, "%d.%d.%d.%d", &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]);
}
You could modify the if conditional block to follow RFC 1918 guidelines, if you need that level of validation.

Answer 3

Swift edition:
func isIPAddressValid(ip: String) -> Bool {
guard let utf8Str = (ip as NSString).utf8String else {
return false
}
let utf8:UnsafePointer<Int8> = UnsafePointer(utf8Str)
var success: Int32
var dst: in_addr = in_addr()
success = inet_pton(AF_INET, utf8, &dst)
if (success != 1) {
var dst6: in6_addr? = in6_addr()
success = inet_pton(AF_INET6, utf8, &dst6);
}
return success == 1
}

Answer 4

A trick you can do is test the return of the inet_aton BSD call like this:
#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;
}
Be aware however that this validates the string if it contains a ip address in any format, it is not restricted to the dotted format.