Question

I see code like this:

@synthesize dataController = _dataController;

What is the purpose of this in a view controller?

Answer 1

If your class needs to store values, it needs someplace in memory to store this data. An instance variable reserves memory for the data your class needs.

Let’s assume you want to add a place for a string or int variable. You can use an instance variable to reserve that memory for the lifetime of the object. Each object will receive unique memory for its variables.

It’s much like a C struct:

struct t_something {
  int a; int b;
};

The struct declares two fields (a and b). Each value may be read and written to, and the struct is large enough to hold its fields.