Programmatic Update of Text Fields

I recently created a small "toy" app in an attempt to learn some Obj-C
and Cocoa programming. It's a multithreaded setup, where multiple
"readers" check out "books" from a "library" -- i.e. threads must
access limited resources from an array. I've got that working
perfectly in CLI form. I can slam a 20-book Library with 500 book-
hungry readers at a time with no problems -- kind of fun. They all end
up reading all the books.

Now I'm taking a shot at providing a GUI for this ridiculous toy. I
have easily been able to set up the interface and use an NSButton to
launch the reader threads. So far, so good. But now I am running into
a problem that I cannot find an answer to, after much searching and
reading.

The difficulty is that I am attempting to use notification from the
library array to update information in the GUI. The idea is that when
the app controller hears a notification from the library, it should
update its labels (sorry, NSTextFields -- I'm coming from Java).
However I used IB to put in these text fields and I cannot figure out
how to access them programmatically.

The current code looks something like this:

<code>
-(void) handleLibraryNotification:(NSNotification*) note{
booksAvailable = [[library bookReport] count];
booksCheckedOut = [arrayOfBooks count] - booksAvailable;

[booksCheckedOutTextField setIntValue:booksAvailable];
[booksAvailableTextField setIntValue:booksCheckedOut];

}
</code>

This doesn't work at all. I realize that the solution here is probably
simple, but I have not been able to discover it. Any help from the
cognoscenti would be welcome.

(btw, I understand from my reading that lots of people use the key-
value system to solve something like this, but for this experiment I
want to do it with notification. Later, if I get the text fields
updating, I will actually make use of all the data packed into the
notification. )

mwt <michaeltaft DeleteThis @gmail.com> wrote:

> The difficulty is that I am attempting to use notification from the
> library array to update information in the GUI. The idea is that when
> the app controller hears a notification from the library, it should
> update its labels (sorry, NSTextFields -- I'm coming from Java).
> However I used IB to put in these text fields and I cannot figure out
> how to access them programmatically.
>
> The current code looks something like this:
>
> <code>
> -(void) handleLibraryNotification:(NSNotification*) note{
> booksAvailable = [[library bookReport] count];
> booksCheckedOut = [arrayOfBooks count] - booksAvailable;
>
> [booksCheckedOutTextField setIntValue:booksAvailable];
> [booksAvailableTextField setIntValue:booksCheckedOut];
>
> }
> </code>

(1) booksCheckedOutTextField and booksAvailableTextField need to be the
names of outlets from this object to the text fields in question (i.e.
instance variables whose values are pointers to those very text fields).
Are they?

(2) I hope you are not doing this on a background thread, as modifying
the interface on a background thread is a no-no.

m.

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