Am 20.01.2010 um 11:34 schrieb Jeremy Pereira:
On 19 Jan 2010, at 23:06, Jens Alfke wrote:
On Jan 19, 2010, at 10:46 AM, Kirk Kerekes wrote:
NSDictionary will use almost any object as a key:
From the docs:
"In general, a key can be any object (provided that it conforms to
the NSCopying protocol...)"
-- and if it is an immutable object, that -copy is just a -retain.
Yes, but he said he wants to use a view as the key. Views are not
immutable, and do copy themselves in response to -copy. Having a
dictionary whose key objects are copies of your live views is not
very useful. (Especially since the copied view will have a
different hashcode from the original one, so you can't even look it
up using the original view anymore...)
Well he could write a category to give him an object that satisfies
all the criteria e.g (written in Mail).
@interface NSView(DictionaryKey)
-(NSNumber*) dictionaryKey;
@end
@implementation NSView(DictionaryKey)
-(NSNumber*) dictionaryKey
{
return [NSNumber numberWithUnsignedLongLong: (unsigned long long)
self];
}
Slightly safer (because it does not make explicit assumptions about
pointer sizes):
-(id) dictionaryKey
{
return [NSString stringWithFormat:@"%p", self];
}
Sorry, couldn't resist ;-)
</jum>
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