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Re: Using NSImages as keys to a dictionary
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Re: Using NSImages as keys to a dictionary


  • Subject: Re: Using NSImages as keys to a dictionary
  • From: "Michael Ash" <email@hidden>
  • Date: Sat, 13 May 2006 17:16:23 -0400

On 5/13/06, Adam R. Maxwell <email@hidden> wrote:

Another way to do this might be to create a CFMutableDictionary with custom callbacks that retain keys instead of copying them, and compares keys based on pointer equality; with toll-free bridging, you'd just treat it as a standard NSMutableDictionary. You have to ensure that the hash of the keys (NSImage instances) doesn't change while they're in the dictionary, though.

Sadly, this doesn't work. While you can indeed treat such a CFMutableDictionary as an NSMutableDictionary, the Cocoa methods will not respect your custom callbacks. In other words, if you create a CFMutableDictionary which does not copy its keys, then do [myCFDict setObject:obj forKey:key], key *will* be copied.

I consider this a bug and have filed it as rdar://4350677 . The
obvious workaround is to use the actual CF functions instead, which is
not really a problem.

Mike
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  • Follow-Ups:
    • Re: Using NSImages as keys to a dictionary
      • From: "Adam R. Maxwell" <email@hidden>
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      • From: Sherm Pendley <email@hidden>
References: 
 >Using NSImages as keys to a dictionary (From: "Lawrence Sanbourne" <email@hidden>)
 >Re: Using NSImages as keys to a dictionary (From: Greg Hurrell <email@hidden>)
 >Re: Using NSImages as keys to a dictionary (From: "Adam R. Maxwell" <email@hidden>)

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