Jeff Decker wrote:
It turns out that the instance of my PolygonShape class in my
PolygonView class does not have any information attached to it.
Did you ever do anything to attach information to it?
Did you assign the variable a value?
I am not sure how to connect the PolygonShape instance, which is
shared by PolygonShape and Controller, to PolygonView. I declared
an instance of PolygonShape *myPolygon in the interface of
PolygonView.h.
Post your code for PolygonView.h and explain what you mean by "shared".
Declaring a variable is not the same as assigning that variable a value.
Declaring a variable is like telling someone "Here's an empy box.
Call it 'shovel'. You will put a shovel in it for digging in the
garden." If you don't give them any shovels, or they don't have an
independent source of shovels, the box remains empty. If you then
tell them "Take the contents of the 'shovel' box and use it to dig a
hole in the garden" I don't think a hole will get dug.
How do I get PolygonView to "know" about the PolygonShape instance
that all the other classes know about?
Be specific. If "the PolygonShape instance that all the other
classes know about" means "the variable myPolygon", then please say
"the variable myPolygon". Otherwise we might wonder if you're
referring to some other PolygonShape instance, and without seeing all
your code, we have no idea what you're talking about.
The code apparently "knows" about the variable named myPolygon, or it
wouldn't compile.
If myPolygon is null, it's probably because no value was ever
assigned to it. That is, nowhere have you executed a statement like:
myPolygon = someExpressionYieldingAPolygon;
If you have executed such a statement before drawRect: is called,
post the code for it and make sure it's actually being executed at
the proper time.
Also make sure something else isn't coming along after the assignment
and before drawRect:, and assigning null.
-- GG
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