reachabilityWithAddress在Objective C编程中不起作用

Question

我想用ip检查服务器是否有效，例如 74.125.71.104（Google的IP）

//分配一个可达性对象

`struct sockaddr_in address;
address.sin_len = sizeof(address);
address.sin_family = AF_INET;
address.sin_port = htons(80);
address.sin_addr.s_addr = inet_addr("74.125.71.104");`

Reachability *reach = [Reachability reachabilityWithAddress:&address];

但那些不起作用。

当我更改为reachabilityWithHostname时，它正在运行。

Answer 1

请导入#include <arpa/inet.h>

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil];
struct sockaddr_in address;
address.sin_len = sizeof(address);
address.sin_family = AF_INET;
address.sin_port = htons(8080);
address.sin_addr.s_addr = inet_addr("216.58.199.174"); //google ip
self.internetReachability = [Reachability reachabilityWithAddress:&address];
[self.internetReachability startNotifier];
[self updateInterfaceWithReachability:self.internetReachability];

修改

根据您的评论，您的可访问性块不会被调用。我总是使用不太了解可达性块的通知。所以我更喜欢使用以下通知。

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil];
struct sockaddr_in address;
address.sin_len = sizeof(address);
address.sin_family = AF_INET;
address.sin_port = htons(8080);
address.sin_addr.s_addr = inet_addr("216.58.199.174");
self.internetReachability = [Reachability reachabilityWithAddress:&address];
[self.internetReachability startNotifier];
[self updateInterfaceWithReachability:self.internetReachability];

现在，只要您的互联网状态发生变化，就会触发可更改性实例触发更改方法：）

- (void) reachabilityChanged:(NSNotification *)note {
    Reachability* curReach = [note object];
    [self updateInterfaceWithReachability:curReach];
}

最后将updateInterfaceWithReachability实现为

- (void)updateInterfaceWithReachability:(Reachability *)reachability {
   NetworkStatus netStatus = [reachability currentReachabilityStatus];
            switch (netStatus)
            {
                case NotReachable: {
                    //not reachable
                }
                break;
                case ReachableViaWWAN:
                case ReachableViaWiFi:        {
                    //reachable via either 3g or wifi
                }
                break;
            }
}

希望这有帮助。