compatibility_alias``The keyword ``@compatibility_alias allows you to define a class name as equivalent to another class name. For example:

@compatibility_alias WOApplication GSWApplication;

tells the compiler that each time it encounters WOApplication as a class name, it should replace it with GSWApplication (that is, WOApplication is just an alias for GSWApplication).

There are some constraints on how this can be used-

• WOApplication (the alias) must not be an existing class;
• GSWApplication (the real class) must be an existing class.