Question

我已经尝试过本网站提供的一些帖子。但在我的iPhone应用程序中，如果没有连接互联网，它不会显示任何错误。它只显示加载视图。我已经使用了以下代码

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
error=nil;
if(error != nil)
{

    UIAlertView * alert;
    if([[error localizedDescription] isEqualToString:@"no Internet connection"])
    {
        alert = [[UIAlertView alloc] initWithTitle:@"No Internet connection" message:[error localizedDescription] delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
    }

    else
    {
        alert = [[UIAlertView alloc] initWithTitle:@"Connection failed" message:[error localizedDescription] delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
    }
    [alert release];
} 
}

即使未连接互联网，也不会显示此警告。谁能帮我？提前致谢

Answer 1

请参阅Apple的this示例代码，了解可达性。

并实施某些必要的方法。

Answer 2

here 是NSUrlConnection目前支持的错误代码

没有互联网连接的错误代码是NSURLErrorNotConnectedToInternet = -1009，

当你遇到NSError *错误

时，你可以在你的情况下使用它

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    if(error != nil)
    {
        if ([error code] == NSURLErrorNotConnectedToInternet) {
          //not connected to internet
       }
    }

}

Answer 3

使用此代码...

定义此

#define AF_INET     2

并实现这一点，

- (BOOL) connectedToNetwork

{

struct sockaddr_in zeroAddress;
bzero(&zeroAddress, sizeof(zeroAddress));
zeroAddress.sin_len = sizeof(zeroAddress);
zeroAddress.sin_family = AF_INET;

// Recover reachability flags
SCNetworkReachabilityRef defaultRouteReachability = SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr *)&zeroAddress);
SCNetworkReachabilityFlags flags;

BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);
CFRelease(defaultRouteReachability);

if (!didRetrieveFlags)
{    
    printf("Error. Could not recover network reachability flags\n");
    return 0;
}   
BOOL isReachable = flags & kSCNetworkFlagsReachable;
BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
return (isReachable && !needsConnection) ? YES : NO;

}

使用bool进行检查，

    BOOL check = [self connectedToNetwork];

然后检查这个条件，

    if (!check) {
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Warning!" message:@"Your internet connection is currently unavailable. Please try to connect later."
                                                   delegate:self cancelButtonTitle:@"Done" otherButtonTitles:nil];
    [alert show];
    [alert release];
}

检查互联网连接是否未显示警报消息

3 个答案: