CODEWITHSUNDEEP
iosobjective-cxcodeautomatic-ref-counting
user3612623
user3612623

Reputation: 265

Programming methods in a non ARC Xcode project

I need to write some methods in a non ARC project in Xcode. I have to implement a NSXMutableDictionary class, a mutable dictionary that can contain up to four key-value pairs. The methods I have to implement are following:

- (void)setObject:(NSObject *)theObject forKey:(NSObject *)theKey;
- (void)removeObjectForKey:(NSObject *)theKey;

I have no clue how to do it, any help would be highly appreciated.

Thanks.

Upvotes: 0

Views: 90

Answers (2)

Duncan C
Duncan C

Reputation: 131398

I agree with @uchuugaka. Create an object that has an NSMutableDictionary inside it. (This is a "has-a" relationship rather than an "is-a" relationship)

The NSDictionary family is what's known as a "class cluster". A class cluster is a public interface that's actually implemented by a set of private classes that you don't see.

Subclassing a class that is part of a class cluster is tricky, and not for beginners. There are a whole set of primitive methods you have to implement in order to create a subclass of a class cluster. Plus, your custom subclass will likely not preform as well as the original class because you won't adapt to different use-cases like the class cluster does.

Upvotes: 1

uchuugaka
uchuugaka

Reputation: 12782

It's not a lot to go on. But with what you provided, it's best to subclass NSObject and have a private property that is an NSMutableDictionary. That allows you to implement all of the same methods of NSMutableDictionary just by declaring them, then in your implementation of each you just call the same method on your actual dictionary property. The difference you add is a check to see if you already have 4 KVPs or not. And any additional methods you need or want.

This is the design pattern of Composition.

Upvotes: 1

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