QLPreviewController loses touch after presenting a modal view controller over it

Question

In an iPad master-detail application (the master is an UITableViewController and the detail a QLPreviewController ) whenever I present a view controller modally and then dismiss it , the QLPreviewController stops receiving touch events or at least reacting to them. So, it's no longer possible to zoom in or out, or "bouncing" an image/document currently being shown, even after another image/document is selected and shown.

Keep in mind that before presenting the view controller modally everything works as expected and it's possible to zoom in/out.

Anyone knows a possible solution for this weird problem?

EDIT: added that this happens after dismissing the view controller presented modally.

EDIT 2: if the presentation style is UIModalPresentationFormSheet , the problem does not occur. It seems to only occur with UIModalPresentationFullScreen .

Answer 1

尽管不是解决此问题的方法，但解决方法是将视图控制器显示为UIModalPresentationFormSheet而不是全屏显示。

Answer 2

Yes that is expected behaviour.

When a ViewController is presented modally (I assume you are presenting something in a form sheet?), it prevents other view controllers receiving touch events.

The other alternative is to have a look at child view controllers as an alternative; but again, their touch events will take precedence over anything underneath.