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Re: [NSMutableDictionary setObject:forKey:] problem
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Re: [NSMutableDictionary setObject:forKey:] problem


  • Subject: Re: [NSMutableDictionary setObject:forKey:] problem
  • From: Joachim <email@hidden>
  • Date: Fri, 21 Oct 2005 00:41:03 -0700

On 19-Oct-05, at 10:44 PM, j o a r wrote:

if ([iPhotoAlbumDict respondsToSelector:@selector (objectForKey:)]) {
[albumDict
setObject:[NSDictionary dictionaryWithObjectsAndKeys:
[[iPhotoAlbumDict objectForKey:@"AlbumId"] copy], @"AlbumId",
[[iPhotoAlbumDict objectForKey:@"Album Type"] copy], @"AlbumType",
[[iPhotoAlbumDict objectForKey:@"PhotoCount"] copy], @"PhotoCount",
nil]
forKey:[iPhotoAlbumDict objectForKey:@"AlbumName"]];



There are additional leaks here that I missed earlier. Note that you're copying the values that you add to the dictionary. Copying here would probably be done be done for two reasons:


1) You want to ensure that the instance you hold is truly your own, and not a mutable instance that someone else can change from under your feet.

2) To increment the retain count of an immutable object.

If you're worried about #1, which I don't think you should have to be for a dictionary that you yourself have restored from a XML file, you need to do this:

    [[[d objectForKey: k] copy] autorelease]

If you did it because of #2, please note that it's not necessary (and in fact wrong -> leak), because these objects will be retained by the dictionary when added to the dictionary. All Cocoa collections works that way. That's also why you changed your code from "initWithObjectsAndKeys:" to "dictionaryWithObjectsAndKeys:" in your latest code revision.

Thank you very much for clarifying that. It's all making more and more sense now. I've now removed the copy messages.


Joachim
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References: 
 >[NSMutableDictionary setObject:forKey:] problem (From: Joachim <email@hidden>)
 >Re: [NSMutableDictionary setObject:forKey:] problem (From: m <email@hidden>)
 >Re: [NSMutableDictionary setObject:forKey:] problem (From: Joachim <email@hidden>)
 >Re: [NSMutableDictionary setObject:forKey:] problem (From: j o a r <email@hidden>)

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