Re: Determining whether a dictionary is mutable or not
Re: Determining whether a dictionary is mutable or not
- Subject: Re: Determining whether a dictionary is mutable or not
- From: Mike Abdullah <email@hidden>
- Date: Fri, 14 Jan 2011 11:15:49 +0000
If you want to test if a dictionary is immutable, you are almost certainly doing it wrong. When passed a dictionary in to a method either:
A) Make a mutable copy if that's what you need
B) -copy it if you want it to be immutable. (This is not inefficient as it sounds because immutable objects implement -copy to do a -retain and return self instead)
On 14 Jan 2011, at 10:48, Tito Ciuro wrote:
> Hello,
>
> Trying to determine whether an NSDictionary is mutable or not fails with these two tests:
>
> // Variable info could be NSDictionary or NSMutableDictionary. Assume it's an NSDictionary.
>
> BOOL isKindOfClass = [info isKindOfClass:[NSMutableDictionary class]];
> BOOL respondsToSelector = [info respondsToSelector:@selector(setObject:forKey:)];
>
> After executing the above statements, both variables 'isKindOfClass' and'respondsToSelector' are set to YES.
>
> When I obtain the class type of 'info', I get:
>
> (gdb) po [info class]
> NSCFDictionary
>
> The question is: if 'info' is an immutable dictionary, why is isKindOfClass and respondsToSelector telling me that it is mutable?
>
> Thanks,
>
> -- Tito
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