Define preprocessor macro for iOS

Question

I have cpp files that are linked as headers to my application. These cpp and header files are used with other applications as well. How do i define pre-processor macros for iphones, so when the application builds it uses the function for ios rather the the other for other platforms.

For example:

How do i define a macro so the connect function uses getaddrinfo_compact when connecting with iOS rather than the simple socket connect function that i used.

bool SocketSender::Connect (const char *host, int port, CApiError &err)
{

errno = 0;
struct hostent *hostinfo;

//struct in6_addr ipv6addr;


hostinfo = gethostbyname(host);

struct addrinfo hints, *res, *res0;
int error,result;
const char *cause = NULL;

memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
//hints.ai_flags = AI_DEFAULT;
hints.ai_protocol = 0;
error = getaddrinfo_compat(host, boost::to_string(port).c_str(), &hints, &res0);
if (error) {
    errx(1, "%s", gai_strerror(error));
    /*NOTREACHED*/
}

getaddrinfo_compact

static int getaddrinfo_compat(
                          const char * hostname,
                          const char * servname,
                          const struct addrinfo * hints,
                          struct addrinfo ** res
                          ) {
int    err;
int    numericPort;

// If we're given a service name and it's a numeric string, set `numericPort` to that,
// otherwise it ends up as 0.

numericPort = servname != NULL ? atoi(servname) : 0;

// Call `getaddrinfo` with our input parameters.

err = getaddrinfo(hostname, servname, hints, res);

// Post-process the results of `getaddrinfo` to work around <rdar://problem/26365575>.

if ( (err == 0) && (numericPort != 0) ) {
    for (const struct addrinfo * addr = *res; addr != NULL; addr = addr->ai_next) {
        in_port_t *    portPtr;

        switch (addr->ai_family) {
            case AF_INET: {
                portPtr = &((struct sockaddr_in *) addr->ai_addr)->sin_port;
            } break;
            case AF_INET6: {
                portPtr = &((struct sockaddr_in6 *) addr->ai_addr)->sin6_port;
            } break;
            default: {
                portPtr = NULL;
            } break;
        }
        if ( (portPtr != NULL) && (*portPtr == 0) ) {
            *portPtr = htons(numericPort);  
        }  
    }  
}  
return err;  
}

Answer 1

Can you define something like

IOSBUILD=1

In the build settings for the target under 'Preprocessor Macros' (set it for all of the configurations eg debug and release).

Then in the C++ code, you can check whether this is an iOS build or not:

#ifdef IOSBUILD
    // Use the compat version.
#else
    // Use the original version.
#endif

That won't upset the other applications, unless they decide to define IOSBUILD too for some reason.