Looking for a framework to add a moveable view in the screen

I have to include to my App a little view with the same behaviour that in FaceTime. When you are having a video call in FaceTime appear a little view with the streaming video of the person who you are talking. I am looking for a framework that let me have a view that it can be moved around the screen like the little view in FaceTime.

Does anyone know of any framework to do this?

Thank you