在WWDC2015上蘋果宣布iOS9將支持純IPv6的網(wǎng)絡(luò)服務(wù)。2016年初開始所有提交到App Store的應(yīng)用必須支持IPv6。這早已不是新鮮事，網(wǎng)上也出了大部分博文供我們參考怎么支持IPv6,關(guān)于Reachability，蘋果也推出了Version 5.0，用來支持IPv6,但細(xì)心的小伙伴可能會(huì)發(fā)現(xiàn)，最新版的Reachability最低的系統(tǒng)要求是iOS 8.0。

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這個(gè)對(duì)于大部分開發(fā)者來說是沒有問題的，但是客戶非要支持iOS7.0怎么辦？小弟我就遇到了這樣的客戶，趕緊在iOS7.0系統(tǒng)上測(cè)試最新的Reachability，希望不要有錯(cuò)，測(cè)試代碼如下：

Reachability *reachability = [Reachability reachabilityForInternetConnection];
NSLog(@"status:%ld",(long)[reachability currentReachabilityStatus]);

測(cè)試結(jié)果往往不如所愿，如下圖，分別在IPv6、IPv4網(wǎng)絡(luò)環(huán)境下使用iOS9.0以及iOS7.0手機(jī)測(cè)試，iOS7.0系統(tǒng)的手機(jī)在IPv6網(wǎng)絡(luò)環(huán)境下是無法得到這確結(jié)果的。（IPv6網(wǎng)絡(luò)環(huán)境搭建請(qǐng)看這里）

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故我開始了對(duì)Reachability的改造之路，目的是想讓它在iOS7上同樣支持IPv6。
改造方法認(rèn)為為：

+ (instancetype)reachabilityForInternetConnection
{
 struct sockaddr_in zeroAddress;
 bzero(&zeroAddress, sizeof(zeroAddress));
 zeroAddress.sin_len = sizeof(zeroAddress);
 zeroAddress.sin_family = AF_INET;
 return [self reachabilityWithAddress: (const struct sockaddr *) &zeroAddress];
}

修改的思路為：

• 獲取設(shè)備IP地址
• 通過IP地址判斷當(dāng)前設(shè)備所處的網(wǎng)絡(luò)環(huán)境
• 如果是IPv6網(wǎng)絡(luò)環(huán)境，則使用struct sockaddr_in6來構(gòu)造zeroAddress。

+ (instancetype)reachabilityForInternetConnection
{
    // IPv4
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;
    
    // 獲取IP地址
    NSString *ipStr = [self getIPAddress];
    NSLog(@"ip address:%@",ipStr);
    if ([ipStr rangeOfString:@"."].location == NSNotFound) {
        // IPv6
        struct sockaddr_in6 zeroAddress;
        bzero(&zeroAddress, sizeof(zeroAddress));
        zeroAddress.sin6_len = sizeof(zeroAddress);
        zeroAddress.sin6_family = AF_INET6;
        return [self reachabilityWithAddress:(const struct sockaddr *)&zeroAddress];
    }
    
    return [self reachabilityWithAddress:(const struct sockaddr *)&zeroAddress];
}

+ (NSString *)getIPAddress {
    NSString *address = @"error";
    struct ifaddrs *interfaces = NULL;
    struct ifaddrs *temp_addr = NULL;
    int success = getifaddrs(&interfaces);    // retrieve the current interfaces - returns 0 on success
    if (success == 0) {
        // Loop through linked list of interfaces
        temp_addr = interfaces;
        while (temp_addr != NULL) {
            // Check if interface is en0 which is the wifi connection on the iPhone
            if ([[NSString stringWithUTF8String:temp_addr->ifa_name] isEqualToString:@"en0"] || [[NSString stringWithUTF8String:temp_addr->ifa_name] isEqualToString:@"pdp_ip0"])
            {
                // IPV4
                if (temp_addr->ifa_addr->sa_family == AF_INET){
                    // Get NSString from C String
                    address = [self formatIPV4Address:((struct sockaddr_in *)temp_addr->ifa_addr)->sin_addr];
                }
                
                // IPV6
                else if (temp_addr->ifa_addr->sa_family == AF_INET6){
                    address = [self formatIPV6Address:((struct sockaddr_in6 *)temp_addr->ifa_addr)->sin6_addr];
                    if (address && ![address isEqualToString:@""] && ![address.uppercaseString hasPrefix:@"FE80"]) break;
                }
            }
            
            temp_addr = temp_addr->ifa_next;
        }
    }
    // Free memory
    freeifaddrs(interfaces);
    return address;
}

//for IPV6
+ (NSString *)formatIPV6Address:(struct in6_addr)ipv6Addr{
    NSString *address = nil;
    
    char dstStr[INET6_ADDRSTRLEN];
    char srcStr[INET6_ADDRSTRLEN];
    memcpy(srcStr, &ipv6Addr, sizeof(struct in6_addr));
    if(inet_ntop(AF_INET6, srcStr, dstStr, INET6_ADDRSTRLEN) != NULL){
        address = [NSString stringWithUTF8String:dstStr];
    }
    return address;
}

//for IPV4
+ (NSString *)formatIPV4Address:(struct in_addr)ipv4Addr{
    NSString *address = nil;
    
    char dstStr[INET_ADDRSTRLEN];
    char srcStr[INET_ADDRSTRLEN];
    memcpy(srcStr, &ipv4Addr, sizeof(struct in_addr));
    if(inet_ntop(AF_INET, srcStr, dstStr, INET_ADDRSTRLEN) != NULL){
        address = [NSString stringWithUTF8String:dstStr];
    }
    return address;
}

修改好之后再次測(cè)試（iOS7系統(tǒng)，IPv6環(huán)境）：

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大功告成。
總結(jié)：如果你的項(xiàng)目也需要適配iOS7.0,那么這個(gè)博客可能有些許幫助，有這個(gè)要求的客戶應(yīng)該少數(shù)。如代碼有問題，希望給予指點(diǎn)。