How can you share ivars between classes.?

Question

In one classes .h i have

NSMutableArray *rountines;

and in another classes .m i want to do something like this

 [routines addOject:@"Hello];

the other class is an ModalViewController type set up.

So, in essence i'd like the .m file of the MVC to be able to read, and edit and do other things to the ivars i declare in the header.

Cheers,

Sam

edit

Another example, which is similar to what im trying to achieve is like an edit screen.

Answer 1

you can either do this by making the ivars you want to share globals (in which case they would be ivars of the singleton class or app delegate class) or by passing a reference to the class you want to modify the ivars of as an argument to a method of the ModalViewController class:

@implementation ModalViewController
......
-(void)addObjectToRoutinesFromClass: (MyClass *)myclass {
        [myclass.routines addObject:@"Hello"];
}

@implementation MyClass
  ......
  ModalViewController *myModalViewController = [[ModalViewController alloc] init];  
[myModalViewController addObjectToRoutinesFromClass:self];

@end

Answer 2

You can't share ivars between classes really. ivar stands for instance variable, and that is a variable that belongs to some particular instance of an object. The way to solve this problem is to allow other objects to access this object's state. This is most commonly done through setter and getter methods. Objective-C 2.0 makes this easier by providing the @property and @synthesize keywords.

If you had access to the object that had the routines array, you could access it through its property (getter method) like this:

[[someObject routines] addObject:@"hello"];