QLPreviewController, how to remove keyCommands?

I'd like to remove the keyCommands of my QLPreviewController. Keys are initialized after itemPreview is initialized in the dataSource.

My solution was to remove them in a loop:

if let qlKeyCommands = self.qLpreviewController.keyCommands {
   for key in qlKeyCommands {
        self.qLpreviewController.removeKeyCommand(key)
    }
}

But unfortunately the functions of the delegat do not seem to be called.

Is there an other way to disable QLPreviewController's keys ?

Thank you