How to apply a progress bar using AFHTTPRequestOperationManager (AFNetworking 2.0), Xcode 5, iOS7?

Question

My code

NSString *const BaseURLString = @"http://192.168.1.202:81//CredentialsModule/CredentialService.asmx/LogInUser";
AFHTTPRequestOperationManager *manager=[AFHTTPRequestOperationManager manager];
NSDictionary *parameters =[[NSDictionary alloc] initWithObjectsAndKeys:@"qwerty",@"UserName",@"qwerty@123",@"Password", nil ] ;
AFJSONRequestSerializer *requestSerializer = [AFJSONRequestSerializer serializer];

[requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Accept"];
[requestSerializer setValue:@"" forHTTPHeaderField:@"Accept-Encoding"];

manager.requestSerializer = requestSerializer;
manager.responseSerializer = [AFJSONResponseSerializer serializerWithReadingOptions:NSJSONReadingAllowFragments];
[ manager  POST:BaseURLString parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) {

NSLog(@"Success: %@", responseObject);

NSLog(@"Content-lent: %lld", [operation.response expectedContentLength]);



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

    NSLog(@"Error: %@",  operation.response);

}];

How can I apply a progress bar? He must be successful.