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Re: NSString Retain Count of 2147483647
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Re: NSString Retain Count of 2147483647


  • Subject: Re: NSString Retain Count of 2147483647
  • From: Hamish Allan <email@hidden>
  • Date: Wed, 24 Jun 2009 15:46:09 +0100

In short, single-character strings are probably implemented as
singletons, but you'll never be able to rely on that, so you might as
well forget you ever knew it. "These one-character strings can be
released pretty much to one's heart's content" is basically
wrong-headed: if you don't balance your retain/alloc/copy/new with
release/autorelease, you have bugs in your code; they may not manifest
themselves because of today's implementation details, but they are
bugs nonetheless.

Hamish

P.S. This is a frameworks question (Cocoa-dev), not a tools question
(XCode-users).

On Wed, Jun 24, 2009 at 3:26 PM, Thomas Wetmore<email@hidden> wrote:
> I know you're not supposed to use retain counts when debugging memory
> issues, but I have found it very (VERY) useful at times. While looking at
> retain counts of NSStrings I have found an oddity that I think I understand,
> but would like confirmation if possible.
>
> When I use NSScanners to chop strings up, whenever I pull a one-character
> string out of a scanner that string has a retain count of 2147483647 (2**32
> - 1). My guess is that there are pre-allocated, one-character strings for
> all (most?) characters that are given this maximum possible value of a
> retain count, the digital equivalent of infinity. Then these one-character
> strings can be released pretty much to one's heart's content but never
> deallocated unless there is an incredible bug, in which case I'm guessing
> that another such one-character string would be allocated to replace it.
>
> Can anyone confirm this suspicion?
>
> Thanks.
>
> Tom Wetmore, curious Xcoder
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References: 
 >NSString Retain Count of 2147483647 (From: Thomas Wetmore <email@hidden>)

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