Question

I’m retrieving an IP address as an unsigned long integer via JSON. I’m trying to then convert this back to human readable form, ie xxx.xxx.xxx.xxx.

Example of what I receive in JSON:

"ip": 704210705

I’m struggling a bit as C was never my forte. I’m getting an EXC Bad Access error on the below:

unsigned long int addr = [[user objectForKey:@"ip"] unsignedLongValue];
struct in_addr *remoteInAddr = (struct in_addr *)addr;
char *sRemoteInAddr = inet_ntoa(*remoteInAddr);

I get the error on the char line (3).

Can anyone give me any advice?

Answer 1

struct in_addr a;
a.s_addr = addr;
char *remote = inet_ntoa(a);

note that the memory pointed to by remote is statically allocated in libc. Therefore, further calls to inet_ntoa will overwrite the previous result.

To get the string properly into obj-c land, use

NSString *str = [NSString stringWithUTF8String:remote];

Or, putting everything together:

NSString *str = [NSString stringWithUTF8String:inet_ntoa((struct in_addr){addr})];