Re: [OBJC newbie] - Intance variable becomes 'invalid'

FROM : Chas Spillar
DATE : Wed May 31 20:56:39 2006

I recommend that you review the memory management sections of the various
Cocoa books available.

If you requested a string without retaining it, then the string will be
released at the time the autorelease pool is released.

In general, if you use the a call that says "create", "copy", "alloc" then
you have a reference and need to release it with either release or
autorelease.  If you use a call that says "Get", etc. you do not have a
reference and can generally only use it within a limited scope.

Chas.


> From: Graham <<email_removed>>
> Date: Wed, 31 May 2006 14:51:03 -0400
> To: Apple CocoaList <<email_removed>>
> Subject: [OBJC newbie] - Intance variable becomes 'invalid'
>
> Just learning OBJC...
>
> I have a class with an NSString * instance variable.
> Class has two methods, method a sets a value into the string, when
> method b is called and tries to access the string it crashes my app.
> gdb says the string instance is 'invalid'.
> How can an instance variable become invalid? What does it even mean?
> I suspect that since OBJC uses pointers everywhere that the instance
> got stamped on somehow?
> I have been living in the safe world of Java for too long I fear.
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