I get warning "UIViewController may not respond to '-vagTouchesBegan:'
(Messages without a matching method signature will be assumed to return 'id'
and accept '...' as arguments)" when I call the view controller from the sub
view
- (void) touchesBegan: (NSSet *)touches withEvent:(UIEvent *)event {
[theViewController vagTouchesBegan:self];
}
even though vagTouchesBegan is properly declared in the controller's .h
-(void)vagTouchesBegan:(id)sender;
Also I follow your advice about retaining loopholes and use
-(void)setViewController:(UIViewController *) vc{
theViewController = vc;
}
So the warning remains puzzling. Note that it's displayed on the sub view .m
page only, after the call line, not after the mention "Succeeded".
Thanks for your tips.
2009/5/30 WT <jrca...@gmail.com>
> On May 30, 2009, at 5:43 PM, Pierre Berloquin wrote:
>
> Declaring in .h
>>
>> -(void)vagTouchesBegan:(id)sender;
>> was my first impulse. But that's not enough.
>>
>
> It's not clear from your two posts which method you're getting a warning
> for. I thought it was for the -vagTouchesBegan method, but you claim it's
> not. Please post the actual warning that you get from XCode.
>
> About the memory problem, I suppose I should receive touchesBegan in the
>> controller and sort out what I get ?
>>
>
> No, that's not what I was referring to. I was referring to the fact that if
> an object of class A retains an object of class B and that same object of
> class B also retains the object of class A which retains it, then you have
> what's called a retain cycle. That may cause you trouble if you're not
> careful.
>
> The view controller already retains its view, so if you're passing the view
> controller object to the view object for it to keep, then the view object
> should NOT retain that view controller object. If what I just said isn't
> completely clear to you, you should read
>
>
> http://devworld.apple.com/documentation/Cocoa/Conceptual/MemoryMgmt/MemoryMgmt.html
>
> If that document is still a bit obscure, then you should search the web for
> more accessible explanations. For instance,
>
>
> http://stackoverflow.com/questions/791322/retain-cycles-why-is-that-such-a-bad-thing
>
> Note that it *is* ok for the view object to have a pointer to its view
> controller. All I'm saying is that you should avoid retaining the view
> controller in its view. Thus, instead of
>
> - (void) setViewController: (UIViewController*) vcontroller
> {
> [viewController release];
> viewController = [vcontroller retain];
> }
>
> (which is the typical setter for objects) you should have
>
> - (void) setViewController: (UIViewController*) vcontroller
> {
> viewController = vcontroller; // Note: no release and no retain
> }
>
> (atypical for objects, but necessary in this case to avoid a retain cycle).
>
> Or, if you prefer to use properties, instead of
>
> @property (readwrite, nonatomic, retain) UIViewController* viewController;
>
> you should use
>
> @property (readwrite, nonatomic, assign) UIViewController* viewController;
>
> Wagner
>
>
> 2009/5/30 WT <jrca...@gmail.com>
>>
>> On May 30, 2009, at 4:40 PM, Pierre Berloquin wrote:
>>>
>>> [theViewController vagTouchesBegan:self];
>>>
>>>> QED
>>>> There's still a warning that the view controller may not respond. But it
>>>> works seamlessly.
>>>> Can I get rid of the warning?
>>>>
>>>>
>>> Yes, by declaring the method -vagTouchesBegan: in the header file of your
>>> view controller class.
>>>
>>> Something to be cautious about when storing in the view a pointer to its
>>> view controller is that you may end up creating a retain cycle, since the
>>> view controller already retains its view. I would recommend that you read
>>> the documentation on memory management to make sure you don't create
>>> unnecessary problems for yourself.
>>>
>>> Wagner
>>>
>>
--
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http://pierre-berloquin.blogspot.com/
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