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NSEnumerator confusion
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NSEnumerator confusion


  • Subject: NSEnumerator confusion
  • From: Hisaoki Nishida <email@hidden>
  • Date: Tue, 20 Sep 2005 16:10:06 -0700

Hi,

I have an NSMutableDictionary whose values I want to modify, but according to the docs I am not allowed to do this *while* enumerating, and instead need to work with a snapshot of the dictionary:

"When this method is used with mutable subclasses of NSDictionary, your code shouldn’t modify the entries during enumeration. If you intend to modify the entries, use the allValues method to create a “snapshot” of the dictionary’s values. Work from this snapshot to modify the values."

What does this mean? Does it mean that I need to modify the snapshot after the enumeration loop? The -allValues method returns an NSArray of values in the dictionary, but I also need access to the keys because I determine which object to modify based on a key. The order isn't even defined, so how am I supposed to work with it?


In code, this is what I would do, if such a thing was allowed:

NSEnumerator *enumerator = [myDictionary objectEnumerator];
id value;

while ((value = [enumerator nextObject]))
{
// ***this is not allowed during enumeration according to docs?
[value removeObjectForKey: @"myNumber"];
[value setObject: [NSNumber numberWithInt: someInt] forKey: @"myNumber"];
}


Thanks,

-hyn _______________________________________________
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