Searching for an object in a set

NSArray doesn't have a "Name field" (whatever that means).

The objects in an NSArray are stored by index, not by "field" or key. You could say that there is an NSString stored at index 3, or index 27, or whatever. It's not possible to say the NSArray has a "Name field".

If you meant NSDictionary instead of NSArray, and you meant there is a key called "Name", then that's a completely different thing.

If you didn't mean an NSDictionary, then please explain exactly how an NSArray has a "Name field".

 

Exactly what are you trying to accomplish with this data structure?

Maybe an NSSet of NSArrays is a poor choice for what you want to accomplish? Beginners often make poor choices of data structures, which turns into a "How do I do X with the Y data structure?" question as difficulties arise. The real question should be "What data structure(s) can I use to accomplish goal Z?" Without knowing the goal, and all the things expected from the data structure, it's hard to answer either question well.

If I had a bunch of NSArrays, where each one's first item was treated as a name, and I had to retrieve an NSArray by name, I'd use an NSDictionary. The key would be the name to retrieve by (i.e. first item in NSArray), and the value would be the NSArray itself. This assumes names are unique, which is somewhat implied by the use of NSSet and the description provided so far. I might not use an NSArray for storing the items; it depends on what I was going to do with the items therein.

 

+1 . A beginner tutorial in data structures that takes maybe 5-6 hours should give you a glimpse at what's logical and then move on from there to read up on what suits you.

 

What you want to do is now clear.

What isn't clear is why you'd use an NSSet. I see nothing in what you want to do that suggests storing the customer orders in an NSSet will do anything for you. You could have stored them in an NSArray, then used an NSPredicate or a block to search for the one array whose first item was SomeUniqueName. Or just enumerate the NSArray and test the first item of each sub-array for SomeUniqueName. I wonder if using NSSet actually prevented you from seeing these relatively simple possibilities.

A linked list is essentially a sequence. An NSArray's elements are sequential. Searching a linked list takes linear time. So does enumerating an NSArray's items.

You should probably read the "Collections Programming Topics" guide:
http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/Collections/Collections.html

The NSDictionary class reference doc has links to sample code projects. Try those.

If necessary, Google search terms: NSDictionary example

 

I don't know why you would think that, assuming you Read The Fine Manual.

The basic class reference docs say that NSSet requires distinct objects, i.e. no two objects in an NSSet can be isEqual: to one another. That's more restrictive than NSArray, not less.

You should probably invest a little time with NSArray's class reference doc. A once-through read seems like a good idea. I suggest after reading the aforementioned "Collections Programming Topics" guide.

NSArray has several methods whose name starts with indexOfObject that would be worth reading. There is also filteredArrayUsingPredicate: that uses an NSPredicate. Or if you dislike blocks for some reason, you could write a fairly simple category on NSArray that performs a "find first item using NSPredicate", which would then be available for all NSArrays.

Nope.