use ffmpeg to record ios screen code example
Example: using ffmpeg on mac to record screen
ffmpeg -f avfoundation -i "2:0" -vf "crop=1024:768:400:800" -pix_fmt yuv420p -y -r 10 out.mov
ffmpeg -f avfoundation -i "2:0" -vf "crop=1024:768:400:800" -pix_fmt yuv420p -y -r 10 out.mov