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Re: A quick memory (release) question
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Re: A quick memory (release) question


  • Subject: Re: A quick memory (release) question
  • From: Paul Harvey <email@hidden>
  • Date: Wed, 1 Feb 2006 09:47:50 +0000

Yes, thanks Scott, that does make sense. With dictionaryWithCapacity, you have not used [NSMutableDictionary alloc], so this is a good sign that it is an autoreleasing setup right?

I've been going over memory management again as I find this whole subject quite difficult to grasp sometimes.


-- Paul Harvey

Lead Programmer
email@hidden

Hiddenfield Software
"Creating useful software for Mac OS X"
www.hiddenfield.com


On Jan 31, 2006, at 13:58, Scott Thompson wrote:

On Jan 31, 2006, at 5:23 AM, Clark Cox wrote:

On 1/31/06, Paul Harvey <email@hidden> wrote:
Two quick examples:

1 NSMutableAttributedString *ns = [[NSMutableAttributedString alloc]
initWithString: chapterText];


2  NSString *lookFor = [[NSString alloc]initWithFormat:@"\n%d",i];

The rule for memory management says that if you obtain an object
through alloc, you have retained it and it must be manually released
at a later point.

Yet methods like initWithFormat create an autoreleased object don't
they?

No, they don't. Both of your examples were obtained from alloc, period. So, you are responsible for releasing them.

Your confusing init methods (which don't generally allocate objects) with class methods that do allocate objects.


For example, if I call:

NSMutableDictionary *myDictionary = [[NSMutableDictionary alloc] initWithCapacity: 10];

Then I get back an object that I am responsible for releasing because I called "alloc"

However, if I call:

NSMutableDictionary *myDictionary = [NSMutableDictionary dictionaryWithCapacity: 10];

Then I get back an object that by the conventions of Cocoa has been autoreleased.

dictionaryWithCapacity is a class method that returns a new object. initWithCapacity is an instance method that you call when an object is new, but it is called on an already allocated object.

Does that make sense?

Scott


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