I know you've been waiting for this moment ever since you saw iOS 7. It's finally here! :)
You can ask your developers to do real time interactive changes of blur radius starting with iOS 10. (And you could animate between blurred and non-blurred since iOS 9.)
GIF is really bad medium to show this, so I suggest you install Xcode 8 (requires free Apple Developer account) and run the sample project.
Blog post | Sample project