Question

If I have a method and class like this:

@implementation Animal
  -(void) move{
    id *object = [object that called move];
   }

@end

Say I have two other classes

@implementation C1
   ...
   [self.animal move]
   ...
@end

@implementation C2
  ...
  [self.animal move]
  ...
@end

Without passing the instance ‘self’ into move, is their some way to get access to self from move?

Answer 1

You cannot do this in Objective-C, the only work around I could suggest is sending a reference of the sender when you message your class, such as:

@implementation Animal
  -(void) move:(id)sender{
    id *object = [object that called move];
   }

@end

Calling:

@implementation C1
   ...
   [self.animal move:self];
   ...
@end

@implementation C2
  ...
  [self.animal move:self];
  ...
@end

You can then use the isMemberOfClass: or isKindOfClass: to determine what type of object the sender is, isKindOfClass will return YES if the class in question is the class you send or a subclass of that. Whereas isMemberOfClass: will only return YES if the class you are messaging is an instance of the class you are sending it

example:

A * aClass; // is just A
[...]

B * bClass; // is a subclass of A
[...]

[aClass isMemberOfClass:[A class]]; // YES 
[bClass isMemberOfClass:[A class]]; // YES


[aClass isKindOfClass:[A class]]; // YES 
[bClass isKindOfClass:[A class]]; // NO