Crash in UIKit: +[UIViewController _viewControllerForFullScreenPresentationFromView:]

[Ada Chan]

<rdar://problem/28384582>

The crash happens in WKActionSheet.mm:

- (void)willRotate
{
    .....
    UIView *view = [_sheetDelegate hostViewForSheet];
    UIViewController *presentingViewController = [UIViewController _viewControllerForFullScreenPresentationFromView:view];
    ...
}

We cannot guarantee that the action sheet belongs in a window, and view could be nil.  Passing nil to -[UIViewController _viewControllerForFullScreenPresentationFromView:] causes an exception to be thrown.

[Ada Chan]

Created attachment 314588 [details]
Patch

[Wenson Hsieh]

Comment on attachment 314588 [details]
Patch

r=me, this check and the explanation seem reasonable, though I think we still need a wk2r+. I don't know any simple way to test this, but we could make a TestWebKitAPI test case that simulates this situation by broadcasting UIWindowWillRotateNotification after presenting a popover in a WKWebView that's been removed from its UIWindow.

[Beth Dakin]

Comment on attachment 314588 [details]
Patch

wk2r=me!

[WebKit Commit Bot]

Comment on attachment 314588 [details]
Patch

Clearing flags on attachment: 314588

Committed r219136: <http://trac.webkit.org/changeset/219136>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.