Re: Using isMemberOfClass with a tree of subclass of NSManagedObject
Re: Using isMemberOfClass with a tree of subclass of NSManagedObject
- Subject: Re: Using isMemberOfClass with a tree of subclass of NSManagedObject
- From: Bill Bumgarner <email@hidden>
- Date: Sat, 28 Jun 2008 16:27:20 -0700
On Jun 28, 2008, at 1:08 PM, Kyle Sluder wrote:
On Sat, Jun 28, 2008 at 2:14 PM, Bill Bumgarner <email@hidden> wrote:
You want -objectForKey: -valueForKey: is for key value coding,
-objectForKey: is for extracting objects from a dictionary.
Shouldn't cause a problem.
I thought the collection classes were smart and treated -valueForKey:
by sending each object in the collection -valueForKey: and compiling
the results in an object arranged in the same way as the original.
That way you could have an array of strings and do something like
[myArray valueForKey:@"length"] to get an array of lengths
corresponding to each instance.
Sort of. Depends on the collection class. The behavior you describe
works for NSArray (and NSSet, IIRC). For NSDictionary, the rules are
slightly different:
...
If key does not start with “@”, invokes objectForKey:. If key does
start with “@”, strips the “@” and invokes [super valueForKey:]with
the rest of the key.
...
Which is, frankly, a bit goofy and, thus, the primary reason why I
would avoid using -valueForKey: on a dictionary.
b.bum
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