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Re: Issues with Inheritance and collections?
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Re: Issues with Inheritance and collections?


  • Subject: Re: Issues with Inheritance and collections?
  • From: Ken Thomases <email@hidden>
  • Date: Fri, 30 Jan 2009 19:51:34 -0600

On Jan 30, 2009, at 5:23 AM, Devraj Mukherjee wrote:

I have two classes DomainLogicBase and Vehicle where Vehicle inherits
from DomainLogicBase [...]

I am adding objects of type Vehicle to an NSMutableArray which are
read up from disk from an SQLite database.

How are you storing/reading them? Are you sure they are complete and valid at this point?


When I try and get the object back out of the NSMutableArray and
access its properties my app crashes. I have tried to use the debugger
and the best I can tell is the properties seem to have invalid values.

If the model class does not inherit from a custom class I have defined
then the app works fine.

Is there something I am missing? Does inheritance do funny things when
I am adding objects of the children class to a collection?

No, inheritance doesn't do "funny things" when you add the objects to a collection.


Is DomainLogicBase derived, directly or indirectly, from NSObject? You might have accidentally forgotten to specify its super class, thus inadvertently making it a root class.

If that's not it, then I suspect memory management problems. You might be over-releasing the objects and the memory is later reused for some other kind of object. Try turning on NSZombieEnabled.

Regards,
Ken

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 >Issues with Inheritance and collections? (From: Devraj Mukherjee <email@hidden>)

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