How to create a floating container

Hello does anyone know how to create a floating container for example even you scroll down or swipe down the pages in your app the container is showing everytime

On this YouTube channel AppGyver tutorial creating a BADASS floating menu for a shopping app - YouTube you can find many ideas approaching what you want to do. The video about what you want to do starts at minute 46:05. If you have any concerns, you can tell the creator of the video @Curiositylab if you need help.