How to check VPN Connectivity in iPhone

I've just found another way to check VPN connection, which wasn't mentioned anywhere. You can use getifaddrs() to get current network interfaces. Then iterate though them and check their names. If any of them contains tap,tun or ppp then user has connected VPN.

  - (BOOL)isVPNConnected
{
    struct ifaddrs *interfaces = NULL;
    struct ifaddrs *temp_addr = NULL;
    int success = 0;

    // retrieve the current interfaces - returns 0 on success
    success = getifaddrs(&interfaces);
    if (success == 0) {
        // Loop through linked list of interfaces
        temp_addr = interfaces;
        while (temp_addr != NULL) {
            NSString *string = [NSString stringWithFormat:@"%s" , temp_addr->ifa_name];
            if ([string rangeOfString:@"tap"].location != NSNotFound ||
                [string rangeOfString:@"tun"].location != NSNotFound ||
                [string rangeOfString:@"ppp"].location != NSNotFound){
                return YES;
            }

            temp_addr = temp_addr->ifa_next;
        }
    }

    // Free memory
    freeifaddrs(interfaces);
    return NO;
}

UPD: on iOS 9 code above is not working. Interfaces are the same, no matter if VPN is connected or not. Try following code in this case:

 - (BOOL)isVPNConnected
{
    NSDictionary *dict = CFBridgingRelease(CFNetworkCopySystemProxySettings());
        NSArray *keys = [dict[@"__SCOPED__"]allKeys];
        for (NSString *key in keys) {
            if ([key rangeOfString:@"tap"].location != NSNotFound ||
                [key rangeOfString:@"tun"].location != NSNotFound ||
                [key rangeOfString:@"ppp"].location != NSNotFound){
                return YES;
            }
        }
        return NO;
}

To fix Timur Suleimanov answer tested on iOS 11 you need to look for IPSec interface;

- (BOOL)isVPNConnected {
    NSDictionary *dict = CFBridgingRelease(CFNetworkCopySystemProxySettings());
    NSArray *keys = [dict[@"__SCOPED__"]allKeys];
    for (NSString *key in keys) {
        if ([key rangeOfString:@"tap"].location != NSNotFound ||
            [key rangeOfString:@"tun"].location != NSNotFound ||
            [key rangeOfString:@"ipsec"].location != NSNotFound ||
            [key rangeOfString:@"ppp"].location != NSNotFound){
            return YES;;
        }
    }
    return NO;
}

If you wanna ping function, you can do something like this;

1. Setup a socket to your internal ip
2. Make the socket non block
3. Using select to check the socket status

It's working for me