Change effect on UIVisualEffectView

is there a way to change the Effect on a UIVisualEffectView? In my App I create a UIVisualEffectView in Storyboards and then I want to change it toLight or Dark on usersettings...

I only see a "initWithEffect" and the "effect" property is readonly :(

So, any Idea on how to solve this?

Thanks, Urkman