// 基准baseURL

    NSURL *baseURL                         = [NSURL URLWithString:@"http://baidu.com/"];

    AFHTTPRequestOperationManager *manager = [[AFHTTPRequestOperationManager alloc] initWithBaseURL:baseURL];

    NSOperationQueue *operationQueue       = manager.operationQueue;

    [manager.reachabilityManager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {

        switch (status) {

            case AFNetworkReachabilityStatusReachableViaWWAN:

            case AFNetworkReachabilityStatusReachableViaWiFi:

                [operationQueue setSuspended:NO];

                // 此处可以发送有网络通知

                NSLog(@"有网络");

                break;

            case AFNetworkReachabilityStatusNotReachable:

            default:

                [operationQueue setSuspended:YES];

                // 此处可以发送断网通知

                NSLog(@"断网了");

                break;

        }

    }];

    // 开始监测网络

    [manager.reachabilityManager startMonitoring];

    // 初始化网址

    NSString *requestAddress =         @"http://api.openweathermap.org/data/2.5/forecast/daily?lat=39.88293652833437&lon=116.4621119300779&lang=zh_cn";

    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];

    // 不带参数的GET请求

    [manager GET:requestAddress

      parameters:nil

         success:^(AFHTTPRequestOperation *operation, id responseObject) {

             NSLog(@"%@", responseObject);

    }

         failure:^(AFHTTPRequestOperation *operation, NSError *error) {

             NSLog(@"%@", error);

    }];