[Interest] Qt/iOS subclassing and/or delegating
Ben Lau
xbenlau at gmail.com
Sat May 30 07:54:59 CEST 2015
You are welcome. By the way, you may submit a feature request, I will vote
for it.
On 30 May 2015 at 00:11, maitai <maitai at virtual-winds.org> wrote:
> I have already spend 3 days on that when the same thing on Android took
> me 5 minutes, so I think I'm not going to swizzle anything soon ;) I might
> give it a try one day though. I believe that should be anyway a part of qt
> API.
>
> Thanks all for your advice and comments
>
> Philippe.
>
>
>
>
> Le 29-05-2015 16:08, Ben Lau a écrit :
>
>
> Depend on what kind of function you should to override. Just checked the
> source code of QIOSViewController , shouldAutorotate is seem to be OK.
> Moreover, Harri Pasanen has suggested swizzling, which could replace a
> method and call the original one by the wrapper.
>
> On 29 May 2015 at 21:43, maitai <maitai at virtual-winds.org> wrote:
>
>> I think you can do that because openUrl is the only method implemented
>> in the original QIOApplicationDelegate. So in fact you added
>> didFinishLaunchingWithOptions and replaced openUrl. But if there were other
>> methods (and QIOViewController has many), you would have been obliged to
>> duplicate them all, at least that's what I understand. Am I wrong?
>>
>>
>>
>>
>> Le 29-05-2015 15:33, Ben Lau a écrit :
>>
>>
>> You may override existing method just like what I did to openUrl and didFinishLaunchingWithOptions
>> on QIOSApplicationDelegate even you don't have the header file.
>>
>>
>>
>>
>> On 29 May 2015 at 21:25, maitai <maitai at virtual-winds.org> wrote:
>>
>>> I tried but didn't succeed. If I understand well (which is far from
>>> being certain), I can only add new methods or properties that way, not
>>> override existing ones unless a protocol is defined that would allow me to
>>> create a delegate on QIOViewController, but there is no as far as I can see.
>>>
>>> I might be wrong, though. I even hope so.
>>>
>>>
>>>
>>>
>>> Le 29-05-2015 15:18, Ben Lau a écrit :
>>>
>>>
>>> Why don't use categories that suggested by people here?
>>>
>>>
>>> On 29 May 2015 at 21:11, maitai <maitai at virtual-winds.org> wrote:
>>>
>>>> Finally got it working... with a bad hack
>>>>
>>>> I cloned QIOSViewController.h and .mm from qt sources (and added qt's
>>>> iOS headers in my include path, I already had core-private and
>>>> gui-private in my pro files) and modified it to do what I want. I also
>>>> had to add a lockedOrientation property to it for some mysterious
>>>> reason...
>>>>
>>>> At least it's doing what I need (i.e. ignore device rotation when I
>>>> decide to). Of course it's a really bad hack and I'm still hoping
>>>> someone can point me to a better solution.
>>>>
>>>> Thanks
>>>> Philippe.
>>>>
>>>>
>>>> Le 29-05-2015 11:24, maitai a écrit :
>>>> > I had a look at QT sources... Basically what I want to do is override
>>>> > QIOSViewController:shouldAutorotate.
>>>> >
>>>> > I tried
>>>> > @interface MyIOSViewController : QIOSViewController
>>>> > @end
>>>> > @implementation MyIOSViewController
>>>> > - (BOOL) shouldAutorotate {
>>>> > NSLog(@"Inside shouldAutorotate");
>>>> > return NO;
>>>> > }
>>>> >
>>>> > It compiles and does not crash (I import QIOSViewController.h), but
>>>> > that
>>>> > all it does...
>>>> >
>>>> >
>>>> > Le 29-05-2015 10:23, Harri Pasanen a écrit :
>>>> >> Compared to C++, Objective-C is very dynamic language and you can do
>>>> >> many things at runtime.
>>>> >>
>>>> >> So you can add methods to existing classes using categories:
>>>> >>
>>>> https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/CustomizingExistingClasses/CustomizingExistingClasses.html
>>>> >>
>>>> >> Or resort to something quite funky to replace existing methods:
>>>> >> https://github.com/rentzsch/jrswizzle
>>>> >>
>>>> >> As to your original question, rotation handling is surprisingly
>>>> tricky
>>>> >> even in pure Objective-C if you want to conditionally rotate. For
>>>> >> instance iOS 8.3 broke some of my code handling that which had worked
>>>> >> fine since iOS 6, pure Objective-C.
>>>> >>
>>>> >> I don't know how Qt hooks into it.
>>>> >>
>>>> >> Harri
>>>> >>
>>>> >> On 29/05/2015 09:41, Robert Iakobashvili wrote:
>>>> >>> On Fri, May 29, 2015 at 8:38 AM, maitai <maitai at virtual-winds.org>
>>>> >>> wrote:
>>>> >>>> Thanks Ben for your reply
>>>> >>>>
>>>> >>>> After much digging I made some progress but I am still looking for
>>>> a
>>>> >>>> way to
>>>> >>>> temporary lock screen auto rotation.
>>>> >>>>
>>>> >>>> I have created my own app delegate to catch openUrl(), and
>>>> >>>> surprisingly it
>>>> >>>> works. I register my app delegate from main.cpp by calling
>>>> something
>>>> >>>> like
>>>> >>>> this:
>>>> >>>>
>>>> >>>> void QtAppDelegateInitialize ()
>>>> >>>>
>>>> >>>> {
>>>> >>>>
>>>> >>>> QtAppDelegate *appDelegate = (QtAppDelegate *)[[UIApplication
>>>> >>>> sharedApplication] delegate];
>>>> >>>>
>>>> >>>> [[UIApplication sharedApplication] setDelegate:[QtAppDelegate
>>>> >>>> sharedQtAppDelegate]];
>>>> >>>>
>>>> >>>> NSLog(@"Created a new appdelegate");
>>>> >>>>
>>>> >>>> }
>>>> >>>>
>>>> >>>>
>>>> >>>>
>>>> >>>> I then found this very interesting post:
>>>> >>>>
>>>> https://forum.qt.io/topic/48745/how-to-get-didfinishlaunchingwithoptions-called-in-ios-delegate/7
>>>> >>>> which links to this bug report: QTBUG-38184.
>>>> >>>>
>>>> >>>> First question: I am now wondering how my delegate can possibly
>>>> work
>>>> >>>> since
>>>> >>>> it seems I can have only one delegate... so what happened to
>>>> >>>> QIOSApplicationDelegate?
>>>> >>>>
>>>> >>>> I then tried various things to add yet another delegate this time
>>>> >>>> based on
>>>> >>>> UINavigationControllerDelegate, but although after much sweat it
>>>> >>>> seems to
>>>> >>>> load, the various methods I am trying to override are never called
>>>> >>>> when I
>>>> >>>> rotate the device.
>>>> >>>>
>>>> >>>> Could it be that I should instead modify/interface
>>>> >>>> QIOSApplicationDelegate
>>>> >>>> itself and not try to create my own delegates?
>>>> >>>>
>>>> >>>> A bit confused at this point, I admit ;)
>>>> >>>>
>>>> >>>> Thanks for any tip
>>>> >>>>
>>>> >>>> Philippe Lelong
>>>> >>>>
>>>> >>>>
>>>> >>>>
>>>> >>>> Le 27-05-2015 20:24, Ben Lau a écrit :
>>>> >>>>
>>>> >>>>
>>>> >>>>
>>>> >>>> On 28 May 2015 at 02:07, maitai <maitai at virtual-winds.org> wrote:
>>>> >>>>> Hello all,
>>>> >>>>>
>>>> >>>>> I've started to port on iOS and need to override some methods,
>>>> like
>>>> >>>>> we
>>>> >>>>> do easily through Java on Qt/Android. I succeeded to implement an
>>>> >>>>> appDelegate in objective-C that works for some events like openURL
>>>> >>>>> and
>>>> >>>>> such, but for instance I also need to lock automatic screen
>>>> >>>>> rotation
>>>> >>>>> in
>>>> >>>>> some circumstances (but not always).
>>>> >>>>
>>>> >>>> Objective-C has a feature to replace the original method of a
>>>> class.
>>>> >>>> So you
>>>> >>>> may just override the method you needed (In case it don't break Qt)
>>>> >>>> Customizing Existing Classes
>>>> >>>>
>>>> >>>> Example Code:
>>>> >>>> quickios/appdelegate.mm at
>>>> 0b067e17dc13b8533ca3f7dd574d7e81ea17a015
>>>> >>>> ·
>>>> >>>> benlau/quickios
>>>> >>>>
>>>> >>>> I have tested to override openURL and didFinishLaunchingWithOptions
>>>> >>>> of
>>>> >>>> AppDelegate with Qt 5.4.1. This method works.
>>>> >>>>
>>>> >>>>> I read that I should somehow override "bool
>>>> >>>>> UINavigationController::shouldRotate()"
>>>> >>>>
>>>> >>>> Never tried. But should be worth to try? I am also be interested
>>>> >>>> with
>>>> >>>> your
>>>> >>>> result.
>>>> >>>>
>>>> >>>>> Should I reimp (subclass?) UINavigationController and how? Or is
>>>> >>>>> there a
>>>> >>>>> way to create a new delegate or even better to extend my current
>>>> >>>>> appDelegate?
>>>> >>>>>
>>>> >>>>>
>>>> >>>>> I'm new to Objective-C as you can guess... Any clue would be
>>>> really
>>>> >>>>> appreciated :)
>>>> >>>>>
>>>> >>>>> Thanks
>>>> >>>>> Philippe Lelong
>>>> >>> Dear Philippe,
>>>> >>>
>>>> >>> Please see the reply Tor Arne inside
>>>> >>>
>>>> >>> https://bugreports.qt.io/browse/QTBUG-42123
>>>> >>>
>>>> >>> That could be an answer - Let it be.
>>>> >>>
>>>> >>> Sincerely,
>>>> >>> Robert
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