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Re: NSData
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Re: NSData


  • Subject: Re: NSData
  • From: email@hidden
  • Date: Thu, 12 Dec 2002 17:36:02 -0800 (PST)

Hello!

Thanks for your reply! And thanks to the other persons
who also replied.

> i dont think, you really need to subcalss NSData.

How can you know?

> Usually it s just fine to make up a new, NSObject
based
> class and USE AN INSTANCE of NSData (or whatever
> other class you think is suitable). So, you can just
> create your class in IB as you are used to.

So basically what you tell me is this:

---------------------------
@interface MyDataObject : NSObject {
NSData * mData;
-- All added members here --
}
--- all added methods here ---
@end
---------------------------

Consequence of what, if I want for instance to access
some data chunk inside of my data, I would have to do
for instance:

---------------------------
@implementation MyDataObject
--- among other methods: ---

- (NSData *)subdataWithRange:(NSRange)range {
return [mData subdataWithRange:range];
}

--- etc ---

@end
---------------------------

or something like this.
This is apparently very weird, because I have then to
reimplement likewise all the methods that I would get
"for free" by inheritance. At least, that's what I would
get in C++. Probably I am missing something...

I thought I can simply write:

---------------------------
@interface MyDataObject : NSData {
-- All added members here --
}
--- all added methods here ---
---------------------------

and then since my object *IS* an NSData, I can call
directly, without having to write the method in
MyDataObject implementation:

[MyDataObjectInstance subdataWithRange:range];

Doesn't it work like this?

> Still, you might want to do it the other way round-
> I think most people do it like this: create your class
> "by hand" as you put it, in PB and then drag the .h
> file into IB. IB will automatically parse it and put
it
> in the class list.

That's good to know. I'll try this.

> From there, you can then instantiate the class, if
> you really need to (I dont even think you need to do
> that for your plain data-class).

Just curious: how can you say that I don't need it?
Please take no offense of this, I got another reply
saying that I shouldn't subclass NData. I would like to
understand the logic behind it. I guess there must be
some very specific reason (e.g. it cannot work because
..., it is highly inefficient because ... and ..., or
some
reason like this).

> If you defined IBActions and IBOutlets, IB will
recognize
> those and you can do all connecting stuff visually, by
> drag-n-drop, in IB.

Thanks!

Pascal
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