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Official Forum for Programming in Objective-C (the iPhone Programming Language) - Stephen Kochan
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Chapter 15
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exercise 15.7 weirdness
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Topic: exercise 15.7 weirdness (Read 1412 times)
Robot-Scott
Jr. Member
Posts: 52
exercise 15.7 weirdness
«
on:
July 19, 2009, 11:55:57 AM »
Man, this is a hard chapter (at least for me).
I haven't even gotten to the part about getting the sum of fractions but I have modified the Fraction class to be an object that holds NSNumbers and I created a FractionArray class to hold collections of Fractions. So, I tested these parts by creating some fractions, adding them to the array, and then printing the array. I then release the memory of the fractions and the fractions' array. However, I keep getting a signal 11 when I include the release of memory for the array. When I edit out that line I get a signal 0 after the program runs. I don't know how to use the debugger really, but I saw that it had highlighted the [pool drain] call so I figure it has to do with some conflict between the array and the autorealease pool. I don't get it because the program looks exactly like the Address Book program with the substitution of fractions for address cards.
I included the project as a zip file.
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"Think globally, act within local variable scope."
skochan
Administrator
Hero Member
Posts: 3114
Re: exercise 15.7 weirdness
«
Reply #1 on:
July 19, 2009, 01:15:04 PM »
You shouldn't be releasing your
numerator
and
denominator
instance variables in your
dealloc
method in your
Fraction
class. You're storing number objects there that are created by Foundation methods. As noted in the text, objects created by Foundation methods other than alloc, copy, or new, are automatically added to the autorelease pool. So they are being over-released.
Cheers,
Steve Kochan
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Robot-Scott
Jr. Member
Posts: 52
Re: exercise 15.7 weirdness
«
Reply #2 on:
July 19, 2009, 06:10:18 PM »
As always, thank you!
I think I'm going to print that rule out about Foundation memory management and post it on my wall.
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"Think globally, act within local variable scope."
webwrx
Newbie
Posts: 41
Re: exercise 15.7 weirdness
«
Reply #3 on:
August 23, 2009, 01:25:27 PM »
Quote from: skochan on July 19, 2009, 01:15:04 PM
As noted in the text, objects created by Foundation methods other than alloc, copy, or new, are automatically added to the autorelease pool.
When you say 'copy', do you mean in the context of @property (copy,...) ?
Ben
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