Hi again. I just stumbled about this problem for another time and rethought
Ulis explanation. The point of my writing is: Ulis explanation is wrong. The
program compiles (with a warning) and runs perfectly fine. So basically Xcode
tells me, that it must know the implementation details, which are not given in
the header file (but may be added in the implementation file -- therefore a
warning rather an error).
Is there a flag to disable such a warning?
Best wishes
Florian
Am Montag, 16 April 2012 um 23:28 schrieb Uli Kusterer:
> On 16.04.2012, at 23:03, Florian Pilz wrote:
> > The import is done in the ".m"-file of HomeTableViewController. But I just
> > found a fault in my sample code anyways: the ".h"-file of
> > HomeTableViewController should have an "@protocol NewFooController"
> > declaration.
> >
> > Corrected sample code for HomeTableViewController.h:
> >
> > #import <UIKit/UIKit.h>
> > @protocol NewFooControllerDelegate;
> > // warning points to line below
> > @interface HomeTableViewController : UITableViewController
> > <NewFooControllerDelegate>
> > @end
> >
>
>
>
> That won't work. When you declare a class as conforming to a protocol, the
> compiler has to know what methods that protocol contains, so it can make sure
> to complain if one of the required methods is missing.
>
> @protocol Foo only works if you want to declare a variable of type id<Foo>
> (but not actually send messages to it). It simply tells the compiler "this
> protocol exists", but not what methods it actually consists of.
>
> It's the same as with plain C struct Foo; and struct Foo { int x; int y; };
> Only the latter can actually be used (because now the compiler knows that
> there is a struct named 'Foo'), but you can declare pointers to the former,
> because for a pointer it only has to know the size of an address, not the
> size of the struct at that address.
>
> Cheers,
> -- Uli Kusterer
> "The Witnesses of TeachText are everywhere..."
> http://www.masters-of-the-void.com
>
>
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