Question

I’m trying to create an app (my first) that generates invoices for me. Originally my idea was to have the following classes:

• User (who all of the following application data belongs to)
• Customer (who to bill: Name, CompanyName, BillingAddress,
  Phone, etc…)
• Task (a line item on the invoice: Name, Description,
  HourlyRate, etc…)
• Invoice (the final output that is comprised of a Customer and
  multiple Tasks)

I thought I could have the user select “Add new customer”, which would create a Customer object and then store that object into a customer array. Same thing with “Add a new task”, which would create a Task object and add it to a task array. I would then be able to create an Invoice object that points to a certain value in the customer array and multiple tasks in the tasks array.

The problem I am running into is that I don’t know how to create a new object each time someone presses “Add New Customer” or “Add a new task”. I’ve tried doing something like this:

Customer *customer = [[Customer alloc] init];
[customer setName:@"John Doe"];
[customer setCompanyName:@"John's Swimming Pools"];

[user1 addCustomer:customer];

[customer setName:@"Jane Smith"];
[customer setCompanyName:@"Cupcakes by Jane"];

[user1 addCustomer:customer];

for (int i = 0; i < [[user1 customers] count]; i++) {
    NSLog(@"%@",[[[user1 customers] objectAtIndex:i] name]);
}

I realize this doesn’t work because the pointer to customer is being overwritten with Jane, so when the array is printed both values in it say “Jane Smith”.

How can I create a new pointer to an object every time the user decides to add a customer/task? Or am I going about this all wrong and should be using arrays for everything instead of classes? I feel like this is very basic OOP and I am struggling to wrap my head around it. Any help would be greatly appreciated, thank you!

Answer 1

If each time some one presses and only one customer is added then why you are adding it twice in the same place?
A simple factory method for adding a customer could be defined in customer class.
At first declare it in Customer.h like:

+(Customer*)createCustomerWithName:(NSString*)name AndCompany:(NSString*)cp;

Then in .m :

+(Customer*)createCustomerWithName:(NSString*)name AndCompany:(NSString*)cp
{
   Customer *customer = [[Customer alloc] init];
   [customer setName:name];
   [customer setCompanyName:cp];
   return customer;
}

Then in your code when you need to add a customer, just call:

[user1 addCustomer:[Customer createCustomerWithName:@"ALan" AndCompany:@"MS"]];

And call it any times you want. Your problem should be solved.

N.B. You must import Customer.h in your class where you call this factory method.