Convert a Fairly Simple Camera Android App to iOS App

I have an Android Camera app with all the original Android Studio Code in Java that I got a freelancer from this website to build. The camera app, films a 4k video, when you stop filming, it takes a screenshot of the last frame and makes it a transparent overlay, so when you start filming again you can see the last frame as a transparent image so you can line the two shots up. I basically want a replica of this app copied but for ios iphone.