一直以來我們獲取IP地址方法都是直接百度一查，或者老代碼裏就已經存在這部分代碼然後直接使用。今天歸納一下常見的兩種方法以及如何選擇：
方式一：
#import <sys/socket.h>
#import <sys/sockio.h>
#import <sys/ioctl.h>
#import <ifaddrs.h>
#import <arpa/inet.h>
- (NSString *)getIPAddress {
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
NSMutableArray *ips = [NSMutableArray array];
int BUFFERSIZE = 4096;
struct ifconf ifc;
char buffer[BUFFERSIZE], *ptr, lastname[IFNAMSIZ], *cptr;
struct ifreq *ifr, ifrcopy;
ifc.ifc_len = BUFFERSIZE;
ifc.ifc_buf = buffer;
if (ioctl(sockfd, SIOCGIFCONF, &ifc) >= 0) {
for (ptr = buffer; ptr < buffer + ifc.ifc_len; ) {
ifr = (struct ifreq *)ptr;
int len = sizeof(struct sockaddr);
if (ifr->ifr_addr.sa_len > len) {
len = ifr->ifr_addr.sa_len;
}
ptr += sizeof(ifr->ifr_name) + len;
if (ifr->ifr_addr.sa_family != AF_INET) continue;
if ((cptr = (char *)strchr(ifr->ifr_name,':')) != NULL) *cptr = 0;
if (strncmp(lastname, ifr->ifr_name, IFNAMSIZ) == 0)continue;
memcpy(lastname, ifr->ifr_name, IFNAMSIZ);
ifrcopy = *ifr;
ioctl(sockfd, SIOCGIFFLAGS, &ifrcopy);
if ((ifrcopy.ifr_flags & IFF_UP) == 0) continue;
NSString *ip = [NSString stringWithFormat:@"%s",inet_ntoa(((struct sockaddr_in *)&ifr->ifr_addr)->sin_addr)];
[ips addObject:ip];
}
}
close(sockfd);
NSString *deviceIP = @"";
for (int i = 0; i < ips.count; i++) {
if(ips.count > 0) {
deviceIP = [NSString stringWithFormat:@"%@", ips.lastObject];
}
}
return deviceIP;
}
方式二：
#import <ifaddrs.h>
#import <arpa/inet.h>
#import <net/if.h>
#define IOS_CELLULAR @"pdp_ip0"
#define IOS_WIFI @"en0"
#define IOS_VPN @"utun0"
#define IP_ADDR_IPv4 @"ipv4"
#define IP_ADDR_IPv6 @"ipv6"
- (NSString *)getLocalIPAddress:(BOOL)preferIPv4 {
NSArray *searchArray = preferIPv4 ?
@[ IOS_VPN @"/" IP_ADDR_IPv4, IOS_VPN @"/" IP_ADDR_IPv6, IOS_WIFI @"/" IP_ADDR_IPv4, IOS_WIFI @"/" IP_ADDR_IPv6, IOS_CELLULAR @"/" IP_ADDR_IPv4, IOS_CELLULAR @"/" IP_ADDR_IPv6 ] :
@[ IOS_VPN @"/" IP_ADDR_IPv6, IOS_VPN @"/" IP_ADDR_IPv4, IOS_WIFI @"/" IP_ADDR_IPv6, IOS_WIFI @"/" IP_ADDR_IPv4, IOS_CELLULAR @"/" IP_ADDR_IPv6, IOS_CELLULAR @"/" IP_ADDR_IPv4 ] ;
NSDictionary *addresses = [self getIPAddresses];
NSLog(@"addresses: %@", addresses);
__block NSString *address;
[searchArray enumerateObjectsUsingBlock:^(NSString *key, NSUInteger idx, BOOL *stop) {
address = addresses[key];
//篩選出IP地址格式
if([self isValidatIP:address]) *stop = YES;
} ];
return address ? address : @"0.0.0.0";
}
- (BOOL)isValidatIP:(NSString *)ipAddress {
if (ipAddress.length == 0) {
return NO;
}
NSString *urlRegEx = @"^([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
"([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
"([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\."
"([01]?\\d\\d?|2[0-4]\\d|25[0-5])$";
NSError *error;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:urlRegEx options:0 error:&error];
if (regex != nil) {
NSTextCheckingResult *firstMatch=[regex firstMatchInString:ipAddress options:0 range:NSMakeRange(0, [ipAddress length])];
if (firstMatch) {
NSRange resultRange = [firstMatch rangeAtIndex:0];
NSString *result=[ipAddress substringWithRange:resultRange];
//輸出結果
NSLog(@"%@",result);
return YES;
}
}
return NO;
}
- (NSDictionary *)getIPAddresses {
NSMutableDictionary *addresses = [NSMutableDictionary dictionaryWithCapacity:8];
// retrieve the current interfaces - returns 0 on success
struct ifaddrs *interfaces;
if(!getifaddrs(&interfaces)) {
// Loop through linked list of interfaces
struct ifaddrs *interface;
for(interface=interfaces; interface; interface=interface->ifa_next) {
if(!(interface->ifa_flags & IFF_UP) /* || (interface->ifa_flags & IFF_LOOPBACK) */ ) {
continue; // deeply nested code harder to read
}
const struct sockaddr_in *addr = (const struct sockaddr_in*)interface->ifa_addr;
char addrBuf[ MAX(INET_ADDRSTRLEN, INET6_ADDRSTRLEN) ];
if(addr && (addr->sin_family==AF_INET || addr->sin_family==AF_INET6)) {
NSString *name = [NSString stringWithUTF8String:interface->ifa_name];
NSString *type;
if(addr->sin_family == AF_INET) {
if(inet_ntop(AF_INET, &addr->sin_addr, addrBuf, INET_ADDRSTRLEN)) {
type = IP_ADDR_IPv4;
}
} else {
const struct sockaddr_in6 *addr6 = (const struct sockaddr_in6*)interface->ifa_addr;
if(inet_ntop(AF_INET6, &addr6->sin6_addr, addrBuf, INET6_ADDRSTRLEN)) {
type = IP_ADDR_IPv6;
}
}
if(type) {
NSString *key = [NSString stringWithFormat:@"%@/%@", name, type];
addresses[key] = [NSString stringWithUTF8String:addrBuf];
}
}
}
// Free memory
freeifaddrs(interfaces);
}
return [addresses count] ? addresses : nil;
}
正常使用都沒有大問題，方式二多了一些功能，多了一些校驗，只是使用 UBSan 分析時，方式一會報一下內存問題，都是指針錯位沒有字節對齊之類的相關檢測報錯。
這些報錯雖然不會直接導致問題，但是按照蘋果官方的描述，可能導致崩潰或性能下降：
Misaligned Pointer (錯位的指針)
Detects when code accesses a misaligned pointer or creates a misaligned reference.
檢測代碼何時訪問錯位的指針或創建錯位的引用。Overview
In Xcode 9 and later, you can use this check to detect reads from, or writes to, a misaligned pointer, or when you create a misaligned reference. A pointer misaligns if its address isn’t a multiple of its type’s alignment. Dereferencing a misaligned pointer has undefined behavior, and may result in a crash or degraded performance.
Alignment violations occur frequently in code that serializes or deserializes data. Avoid this issue by using a serialization format that preserves data alignment.
在Xcode 9和之後更高版本中，你可以使用這個檢查來檢測從一個錯位的指針讀取或寫入，或者當你創建一個錯位的引用時，如果一個指針的地址不是其類型對齊的倍數，那麼它就會出現錯位。解除一個錯位的指針有未定義的行爲，並可能導致崩潰或性能下降。
在序列化或反序列化數據的代碼中，經常發生違反對齊方式的情況。通過使用保留數據對齊的序列化格式來避免這個問題。
所以綜上還是建議使用方式二來獲取ID地址（都是本地地址），要獲取公網地址可以使用淘寶的API：
- (NSString *)getNetworkIPAddress {
//方式一：淘寶api
NSURL *ipURL = [NSURL URLWithString:@"http://ip.taobao.com/service/getIpInfo.php?ip=myip"];
NSData *data = [NSData dataWithContentsOfURL:ipURL];
NSDictionary *ipDic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
NSString *ipStr = nil;
if (ipDic && [ipDic[@"code"] integerValue] == 0) {
//獲取成功
ipStr = ipDic[@"data"][@"ip"];
}
return (ipStr ? ipStr : @"0.0.0.0");
}