重新启动模拟器解决了我的问题。

当传递一个NSURLRequest到一个NSURLSession而没有设置请求的HTTPMethod时，我击中了这个错误。

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:urlComponents.URL];

ErrorDomain =NSURLErrorDomain Code=-1005 "The network connection was lost."

不过，添加HTTPMethod，连接就可以正常工作了

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:urlComponents.URL];
[request setHTTPMethod:@"PUT"];

如果问题发生在设备上，检查流量是否通过代理(设置> Wi-Fi > (info) > HTTP代理)。我已经设置好了与Charles一起使用的设备，但忘记了代理。似乎没有Charles实际运行，就会出现这个错误。

I was getting this error as well, but on actual devices rather than the simulator. We noticed the error when accessing our heroku backend on HTTPS (gunicorn server), and doing POSTS with large bodys (anything over 64Kb). We use HTTP Basic Auth for authentication, and noticed the error was resolved by NOT using the didReceiveChallenge: delegate method on NSURLSession, but rather baking in the Authentication into the original request header via adding Authentiation: Basic <Base64Encoded UserName:Password>. This prevents the necessary 401 to trigger the didReceiveChallenge: delegate message, and the subsequent network connection lost.

我在iOS 8设备上运行时也遇到了这个问题。 这里有更详细的说明，似乎是iOS试图使用已经超时的连接。 我的问题与那个链接中解释的Keep-Alive问题不一样，但它似乎是相同的最终结果。

我已经通过运行一个递归块纠正了我的问题，每当我收到一个错误-1005，这使得连接最终通过，即使有时递归可以在连接工作之前循环100+次，然而，它只增加了一秒钟的运行时间，我打赌这只是需要调试器为我打印NSLog的时间。

下面是我如何用AFNetworking运行递归块: 将此代码添加到连接类文件中

// From Mike Ash's recursive block fixed-point-combinator strategy https://gist.github.com/1254684
dispatch_block_t recursiveBlockVehicle(void (^block)(dispatch_block_t recurse))
{
    // assuming ARC, so no explicit copy
    return ^{ block(recursiveBlockVehicle(block)); };
}
typedef void (^OneParameterBlock)(id parameter);
OneParameterBlock recursiveOneParameterBlockVehicle(void (^block)(OneParameterBlock recurse, id parameter))
{
    return ^(id parameter){ block(recursiveOneParameterBlockVehicle(block), parameter); };
}

然后这样使用它:

+ (void)runOperationWithURLPath:(NSString *)urlPath
            andStringDataToSend:(NSString *)stringData
                    withTimeOut:(NSString *)timeOut
     completionBlockWithSuccess:(void (^)(AFHTTPRequestOperation *operation, id responseObject))success
                        failure:(void (^)(AFHTTPRequestOperation *operation, NSError *error))failure
{
    OneParameterBlock run = recursiveOneParameterBlockVehicle(^(OneParameterBlock recurse, id parameter) {
        // Put the request operation here that you want to keep trying
        NSNumber *offset = parameter;
        NSLog(@"--------------- Attempt number: %@ ---------------", offset);

        MyAFHTTPRequestOperation *operation =
            [[MyAFHTTPRequestOperation alloc] initWithURLPath:urlPath
            andStringDataToSend:stringData
            withTimeOut:timeOut];

        [operation setCompletionBlockWithSuccess:
            ^(AFHTTPRequestOperation *operation, id responseObject) {
                success(operation, responseObject);
            }
            failure:^(AFHTTPRequestOperation *operation2, NSError *error) {
                if (error.code == -1005) {
                    if (offset.intValue >= numberOfRetryAttempts) {
                        // Tried too many times, so fail
                        NSLog(@"Error during connection: %@",error.description);
                        failure(operation2, error);
                    } else {
                        // Failed because of an iOS bug using timed out connections, so try again
                        recurse(@(offset.intValue+1));
                    }
                } else {
                    NSLog(@"Error during connection: %@",error.description);
                    failure(operation2, error);
                }
            }];
        [[NSOperationQueue mainQueue] addOperation:operation];
    });
    run(@0);
}

您将看到我使用了一个AFHTTPRequestOperation子类，但添加了您自己的请求代码。重要的部分是调用递归(@offset.intValue+1));使该块再次被调用。

解决我的问题是重新启动模拟器，并重置内容和设置。