将其捕获到失败"块中，然后检查状态码并重新进行身份验证

Catch it in Failure block , and check for the status code and re-do the authentication

    RKObjectRequestOperation *requestOp = [[RKObjectRequestOperation alloc] initWithRequest:request responseDescriptors:@[getObjResp]];

            [requestOp setCompletionBlockWithSuccess:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
                ....
                }
            } failure:^(RKObjectRequestOperation *operation, NSError *error){
// Here your status code check                
// Here your retry-code
                }