统一处理AFNetwork的返回
[[NSNotificationCenter defaultCenter] addObserver:selfselector:@selector(networkRequestDidStart:) name:AFNetworkingOperationDidStartNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:selfselector:@selector(networkRequestDidFinish:) name:AFNetworkingOperationDidFinishNotification object:nil];
#if (defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >=70000) || (defined(__MAC_OS_X_VERSION_MAX_ALLOWED) && __MAC_OS_X_VERSION_MAX_ALLOWED >=1090)
[[NSNotificationCenter defaultCenter] addObserver:selfselector:@selector(networkRequestDidStart:) name:AFNetworkingTaskDidResumeNotification object:nil];
[[NSNotificationCenterdefaultCenter] addObserver:selfselector:@selector(networkRequestDidFinish:) name:AFNetworkingTaskDidCompleteNotification object:nil];
#endif