即使我们确实有互联网连接，可达性有时也会失败 [英] Reachability sometimes fails, even when we do have an internet connection

问题描述

我已经搜索过但看不到类似的问题。

I've searched but can't see a similar question.

我已根据可达性示例添加了一种检查互联网连接的方法。它大部分时间都可以工作，但是当安装在iPhone上时，即使我有互联网连接也常常会失败（只有当使用3G / EDGE时 - WiFi就可以了）。

I've added a method to check for an internet connection per the Reachability example. It works most of the time, but when installed on the iPhone, it quite often fails even when I do have internet connectivity (only when on 3G/EDGE - WiFi is OK).

基本上下面的代码返回NO。

Basically the code below returns NO.

如果我切换到另一个应用程序，比如Mail或Safari，然后连接，然后切换回应用程序，然后代码说互联网是可以访问的。有点似乎需要'轻推'。

If I switch to another app, say Mail or Safari, and connect, then switch back to the app, then the code says the internet is reachable. Kinda seems like it needs a 'nudge'.

之前有人见过这个吗？有什么想法？

Anyone seen this before? Any ideas?

非常感谢
James

Many thanks James

+ (BOOL) doWeHaveInternetConnection{

BOOL success;
// google should always be up right?!
const char *host_name = [@"google.com" cStringUsingEncoding:NSASCIIStringEncoding];

SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL,
                                                                            host_name);
SCNetworkReachabilityFlags flags;
success = SCNetworkReachabilityGetFlags(reachability, &flags);
BOOL isAvailable = success && (flags & kSCNetworkFlagsReachable) && !(flags & kSCNetworkFlagsConnectionRequired);

if (isAvailable) {
    NSLog(@"Google is reachable: %d", flags);
}else{
    NSLog(@"Google is unreachable");
}

return isAvailable;

}

推荐答案

看起来你已经从Apple示例代码中删除了一些基本的可访问性代码。当你完好无损地执行此操作会发生什么？

Looks like you've stripped out some basic reachability code from the Apple example code. What happens when you leave it intact and do this?

Reachability *hostReach = [[Reachability reachabilityWithHostName: @"www.apple.com"] retain];

NetworkStatus netStatus = [hostReach currentReachabilityStatus];

if (netStatus == NotReachable)
{
    NSLog(@"NotReachable");
}

if (netStatus == ReachableViaWiFi)
{
    NSLog(@"ReachableViaWiFi");
}

if (netStatus == ReachableViaWWAN)
{
    NSLog(@"ReachableViaWWAN");
}

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