Is there a way to create linked list in objective c. I'm a newbie and so far I've researched in apple developer guides, there isn't any function predefined for linked list. Is doubly linked list same as linked list in objective-c?
Please help.
2 Answers
First thing to keep in mind is that Objective-C is C, it's just a lot more, too.
Next thing is that Objects are passed around as (essentially) pointers (which the compiler knows point to objects).
So you can certainly make and manage your own linked list, and you can do it with structs or objects. With objects (perhaps preferred), just create a @property in the class for the "next" object, and use it as you please. Similarly for a doubly-linked list, have a @property for previous.
Perhaps one of the best arguments against caring about liked lists in Objective-C is that usually you have the Cocoa Frameworks at hand, and there is such rich host of features which we used to have to implement ourselves with linked lists. For instance, the conceptually simple NSMutableArray, or NSDictionary are great examples of well-built components which usually spare us the need for linked lists. Going further, Core Data, etc...
A simple abstract linked list class might look like this:
@interface LinkedNode : NSObject
@property (nonatomic, strong) id nextNode;
@end
then you use it as you would expect:
id currentNode = myFirstNode;
do {
[currentNode someMessage];
}
while(currentNode = currentNode.nextNode);
Keep in mind that this is really no "better" than doing it with structs. For the "better" business, move to the Cocoa classes and implement at a "higher level", so-to-speak.
5 Comments
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On the other hand, I have had several problems where a linked list was, if not the only way, the most straight-forward and efficient way. And it's a good technique to learn -- something to have in your "toolkit".
user1661826
Thank you. I shall try using this.
Chris Trahey
Yes, I am certainly an advocate of learning with the linked list and really the notion of dynamic data structures. I got the impression that OP was familiar with linked lists but not Objective-C... Still it seems fun to do a more robust abstract linked list implementation with objects.
Nicolas Miari
Agreed... Coding your own linked list once is "Programming 101". Every one should do it once.
Analog File
Agreed ... in part. Because learning a functional language (lisp, scheme etc.) should also be considered programming 101. And then you probably should concentrate on using lists instead of implementing them :p
Please check my implementation of some of the common data structures like linked list, stack, binary search tree in objective C. https://github.com/udaypatial/Data-Structures-in-Objective-C
NSArraynot do the job? If you really must create your own linked list you can look at any C linked list examples, Objective-C is a superset of C.