[Webkit-unassigned] [Bug 165225] UIViewController with WKWebView presented modally causes the presented UIViewController to be dismissed.

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=165225

--- Comment #28 from Brad Wright <bwright2 at apple.com> ---
(In reply to comment #26)
> (In reply to comment #25)
> > Comment on attachment 303130 [details]
> > Patch
> > 
> > View in context:
> > https://bugs.webkit.org/attachment.cgi?id=303130&action=review
> > 
> > > Source/WebKit2/UIProcess/ios/forms/WKFileUploadPanel.mm:391
> > > +    // dismiss any viewController that is being presented. This is works all VC, popovers, etc.
> 
> This is works for all VC.  Missed the for, in the comment.
> > 
> > Normally we would want to use a capital D in this kind of sentence-style
> > comment.
> > 
> > VC is not normally an abbreviation we use for view controller in WebKit code.
> > 
> > "This is works all", is not grammatically correct.
> > 
> > > Source/WebKit2/UIProcess/ios/forms/WKFileUploadPanel.mm:394
> > > +    UIViewController *presentedViewController = [UIViewController _viewControllerForFullScreenPresentationFromView:_view];
> > > +    if (presentedViewController)
> > > +        [presentedViewController dismissViewControllerAnimated:NO completion:nil];
> > 
> > Would be nice to define the variable inside the "if" since this is C++ code.
> > In fact, I personally would use auto instead of writing out UIViewController
> > * for the type of the variable.
> > 
> > > Source/WebKit2/UIProcess/ios/forms/WKFileUploadPanel.mm:508
> > > +    // Clear out any previous view controller reference, to prevent calling dismiss on a view controller that
> > > +    // was no longer being presented. Don't save a reference to the UIDocumentMenuViewController as it is self dismissing.
> > > +    _presentationViewController = nil;
> > 
> > I don’t understand this comment and therefore don’t understand the code.
> 
> So what happening is that the _presentationViewController is used to called
> in:
> 
> - (void)_dismissDisplayAnimated:(BOOL)animated
> {
>     if (_presentationPopover) {
>         [_presentationPopover dismissPopoverAnimated:animated];
>         [_presentationPopover setDelegate:nil];
>         _presentationPopover = nil;
>     }
> 
>     if (_presentationViewController) {
>         [_presentationViewController dismissViewControllerAnimated:animated
> completion:^{
>             _presentationViewController = nil;
>         }];
>     }
> }
> 
> 
> The UIDocumentMenuViewController dismisses itself, so when
> _presentationViewController dismissViewControllerAnimated:animated is called
> in this function, it dismisses the WKWebView when is presented modally. 
> That's why it's set to nil in this function, so that the errant code path is
> never executed.
> > 
> > On iPhone, the method called just before this will call
> > _presentFullscreenViewController. Then this line of code will clear out the
> > reference to that just-presented view controller. Given that, why does this
> > comment talk about clearing out a "previous view controller reference"?


Inside the call stack this is the reference that needs to be cleared out.

1. when this called
- (void)_showDocumentPickerMenu
2.It then calls this:
- (void)_presentMenuOptionForCurrentInterfaceIdiom:(UIViewController *)viewController
3. Finally, inside here the reference is saved.
- (void)_presentFullscreenViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    ...
    _presentationViewController = [UIViewController 
...
}

4. When we return up the stack, I need to unset the reference.

- (void)_showDocumentPickerMenu


I put this comment and the nil reference as close together as possible to minimize future errors.

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