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我正在使用未启用 iOS Direct-WiFi 的设备对我的 iOS 设备进行对等。在我的 iOS 应用程序中，我喜欢启动与远程服务器（即非 iOS 设备的服务器）的连接。为此，首先我需要将我的读写流绑定到主机 IP 和端口，如下所示：

NSInputStream *inputStream;
NSOutputStream *outputStream;

CFReadStreamRef rdStream;
CFWriteStreamRef wrStream;
NSString *ipAddr = ???    /* not know at design time */
UInt32 portNum = 4210;    /* specified at design time */

CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, (__bridge CFStringRef)ipAddr, portNum, &rdStream, &wrStream);

inputStream = (__bridge NSInputStream *)rdStream;
outputStream = (__bridge NSOutputStream *)wrStream;

...然后对于每个流，我设置委托，在运行循环中安排，然后打开。现在它们可以使用了。显然，在我的 iOS 设备中，我转到设置内置应用程序并选择我正在对等的服务器的 WiFi，这样我的 iOS 设备和其他设备将在同一个网络上。

我的问题是在我的应用程序设计时服务器 IP 地址是未知的，所以我想在我的应用程序运行时以编程方式找出这个 IP 。可能吗？如果是这样，请给我一个想法。

谢谢

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1 回答 1

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这将为您提供一系列 IP。出于我的目的，第二个元素是主机名的 iP：

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#import <CFNetwork/CFNetwork.h>
#import <netinet/in.h>
#import <netdb.h>
#import <ifaddrs.h>
#import <arpa/inet.h>
#import <net/ethernet.h>
#import <net/if_dl.h>

...

    const char* hostnameC = [yourHostName UTF8String];

struct addrinfo hints, *res;
struct sockaddr_in *s4;
struct sockaddr_in6 *s6;
int retval;
char buf[64];
NSMutableArray *result; //the array which will be return
NSMutableArray *result4; //the array of IPv4, to order them at the end
NSString *previousIP = nil;

memset (&hints, 0, sizeof (struct addrinfo));
hints.ai_family = PF_UNSPEC;//AF_INET6;
hints.ai_flags = AI_CANONNAME;
//AI_ADDRCONFIG, AI_ALL, AI_CANONNAME,  AI_NUMERICHOST
//AI_NUMERICSERV, AI_PASSIVE, OR AI_V4MAPPED

retval = getaddrinfo(hostnameC, NULL, &hints, &res);
if (retval == 0)
{

    if (res->ai_canonname)
    {
        result = [NSMutableArray arrayWithObject:[NSString stringWithUTF8String:res->ai_canonname]];
    }
    else
    {
        //it means the DNS didn't know this host
        return;
    }
    result4= [NSMutableArray array];
    while (res) {
        switch (res->ai_family){
            case AF_INET6:
                s6 = (struct sockaddr_in6 *)res->ai_addr;
                if(inet_ntop(res->ai_family, (void *)&(s6->sin6_addr), buf, sizeof(buf))
                   == NULL)
                {
                    NSLog(@"inet_ntop failed for v6!\n");
                }
                else
                {
                    //surprisingly every address is in double, let's add this test
                    if (![previousIP isEqualToString:[NSString stringWithUTF8String:buf]]) {
                        [result addObject:[NSString stringWithUTF8String:buf]];
                    }
                }
                break;

            case AF_INET:
                s4 = (struct sockaddr_in *)res->ai_addr;
                if(inet_ntop(res->ai_family, (void *)&(s4->sin_addr), buf, sizeof(buf))
                   == NULL)
                {
                    NSLog(@"inet_ntop failed for v4!\n");
                }
                else
                {
                    //surprisingly every address is in double, let's add this test
                    if (![previousIP isEqualToString:[NSString stringWithUTF8String:buf]]) {
                        [result4 addObject:[NSString stringWithUTF8String:buf]];
                    }
                }
                break;
            default:
                NSLog(@"Neither IPv4 nor IPv6!");

        }
        //surprisingly every address is in double, let's add this test
        previousIP = [NSString stringWithUTF8String:buf];

        res = res->ai_next;
    }
}else{
    NSLog(@"no IP found");
    return;
}

...

于 2012-12-14T00:42:13.473 回答