Re: newbie NSMutable dictionary subclass question
Re: newbie NSMutable dictionary subclass question
- Subject: Re: newbie NSMutable dictionary subclass question
- From: Jean-Daniel Dupas <email@hidden>
- Date: Mon, 17 Nov 2008 11:38:58 +0100
Can the value part of a key-value pair in an NSMutableDictionary be
a literal NSString, like @"name"?
It would seem so, because this works or at least doesn't crash:
NSMutableDictionary *bobo;
bobo = [[NSMutableDictionary alloc] init];
[bobo setValue:@"root" forKey:@"name"];
However, I have a class derived from NSMutableDictionary, and it is
crashing when I try to do the same thing:
@interface myClass : NSMutableDictionary {
}
@end
myClass *tree;
tree = [[myClass alloc] init];
[tree setValue:@"root" forKey:@"name"];
Why does that crash when the first does not? Are subclasses
required to have member variables, or can they just have new
functions? Mine don't have any variables, maybe that is the problem?
Look like someone that did not read the fondamental before coding ;-)
Short answer: because NSDictionary is a class cluster.
Long answer here:
http://developer.apple.com/documentation/Cocoa/Conceptual/CocoaFundamentals/CocoaObjects/chapter_3_section_9.html
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