Question

I have read about how Objective-C runtime works, so please comment if I misunderstood something.

Let’s say I have class called Person. That class may or not have method getSex.

Person *p = [[Person alloc]init];

Here the memory is allocated for Person instance (isa is created also which points to class Person), init is used to initialize Person ivar’s

[p getSex];

Here objc_msgSend(Person,@selector(getSex) is called on Person class.
If Person class not have such method the runtime look for that method in Person root class and so on. When the method is found IMP is called which is a pointer to method block code. Then the method is executed.

Is that correct ?

Answer 1

Yes, everything is correct, except the behavior of init may or may not initialize all its member variables such that the accessors return valid results, although it is reasonable to guess that it initializes properties unless told otherwise.