Null result on Converting NSData to NSString

Question

I am facing a problem when converting NSData to NSString. I'm using UTF8Enconding but the result is null!!

Here is the data I receive <100226ab c0a8010b 00000000 00000000> it must be either 192.168.1.11 or 192.168.1.17.

This is the method I use to convert :

 NSString *ipAddress = [[NSString alloc] initWithData:address encoding:NSUTF8StringEncoding];

Is there anything wrong?!

By the way, This the did receive data delegate of GCDAsyncUdpSocket library.

Answer 1

From the documentation of GCDAsyncUdpSocket:

The localAddress method returns a sockaddr structure wrapped in a NSData object.

The following code unwraps the data to a sockaddr structure and converts the IP address to a NSString. It works with IPv4 and IPv6 addresses.

#include <sys/socket.h>
#include <netdb.h>

NSData *data = ...; // your data
NSLog(@"data = %@", data);

// Copy data to a "sockaddr_storage" structure.
struct sockaddr_storage sa;
socklen_t salen = sizeof(sa);
[data getBytes:&sa length:salen];

// Get host from socket address as C string:
char host[NI_MAXHOST];
getnameinfo((struct sockaddr *)&sa, salen, host, sizeof(host), NULL, 0, NI_NUMERICHOST);

// Convert C string to NSString:
NSString *ipAddress = [[NSString alloc] initWithBytes:host length:strlen(host) encoding:NSUTF8StringEncoding];
NSLog(@"strAddr = %@", ipAddress);

Output:

data = <100226ab c0a8010b 00000000 00000000>
strAddr = 192.168.1.11