VM Tracker Swapped memory

Question

What is the "Swapped Size" in Xcode VM Tracker instrumentation tool on iOS? Does iOS 10 have swap?

Answer 1

It refers to the compressed memory, which is how iOS deals with unused pages. Instead of totally moving unused pages from RAM to drive, it compresses them and keeps compressed bytes in RAM. However, one important thing to note is that your app's total memory footprint will still be computed using the UNCOMPRESSED size. The moment you access the page again, it will get decompressed again in RAM. So the "swap size" in all the tools actually refers to the UNCOMPRESSED size of unused pages. On iOS, ultimately your memory footprint = dirty + swap size.

Source: https://developer.apple.com/videos/play/wwdc2018/416/?time=125