Hi Graham and all,
I also tried to use bindings, which I've made work well for linking
text views, table columns, even outline view columns, to data in my
model. But I can't seem to set up bindings to link an instance
variable in one controller to another controller. So I guess
bindings are only for linking view objects to model objects, yes?
First, forget bindings... bindings is really an advanced topic, so I
suggest you'll be better off leaving it alone for now. Bindings are
mostly designed for handling the view<-->controller connections.
Actually, as I mentioned, I've had great success with bindings for
linking view objects to data. I am actually surprised at how bindings
seems to always be taught as an advanced topic, whereas I think it
should be introduced much earlier to newbie Cocoa programmers,
especially since it eliminates so much code, but that's another story.
I just wondered whether bindings could be used to link instance
variables in two controllers, but I guess not.
In this case you have a controller<-->controller connection, which
is likely to be a lot simpler.
You have two controllers. Each controller can have an IBOutlet to
the other one. Just declare the outlets then wire them up in your
nib, e.g:
I kinda got that, but missed what exactly to wire up...
// MyController.h
@class MyDocument;
@interface MController : NSObject
{
IBOutlet MyDocument* the_document;
}
...
@end
...
ahh, now that makes sense. That's what I was missing. I was trying to
add IBOutlets for instance variables but needed to instead add
IBOutlets for the class (eg MyDocument). Has this been documented
anywhere? I couldn't find it. I would have thought it a common
requirement, or is there a better approach to sharing data between
controllers in the same nib?
When I try to compile the above, I get an error:
expected specifier-qualifier-list before 'MyDocument'
If I change the "MyDocument*" to "id", it works, but what's the problem?
Once you have added the outlets to your classes, they will be
visible in IB, so just ctrl-drag from one object to the other and
choose the outlet to connect it. In the .m files, #import the header
for the other class:
#import "MyDocument.h"
Is this really necessary? It compiles without it. I did it anyway.
In your code, you can now do things like this, from your controller:
NSString* file = [the_document fileString];
the_document is showing as value nil. It doesn't seem to be linked to
the instance of MyDocument. Am I missing something?
Thanks for all your help,
Tom
BareFeet
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