Can data be retrieved from 'swaps' or 'cache'?

BDAqua wrote:

The only very thin possibility if not using an SSD, wouold be to immediately quit using the drive & try aData recovery App.

If using an SSD then past things are really immediately gone.

Thanks, I use a standard hard drive but don't 'data recovery' apps work strictly on disk files? My understanding of what happened in my case (text in a TextEdit file was lost when a 'revert changes' save was done) is that the lost data never made it to disk.

If TextEdit doesn't automatically save data, I'm baffled as to why TextEdit file content is preserved without my actively executing a 'save', and where it gets saved to if not 'to disk'.

When I close a TextEdit file without saving, any text I added is retained. I've specifically tested that and is one reason why I thought 'revert changes' would only have removed what hadn't been included in the last autosave -- which would have been (or so I thought) pretty much just all the 'white space' I mentioned in my original post.*

* Is there any way to recover data in a TextEdit file that was closed with 'revert changes'?

Thanks, VikingOSX for that detailed explanation, but are autosave and versioning in OS Mojave?

(I posted this in the Earlier Operating Systems forum and am not aware of those functions in my version of TextEdit.)

In Mojave, the ‘revert changes’ function I was referring to is the one TextEdit displays when a file is closed without the user having first saved it.

If there is any kind of autosave and versioning in my TextEdit, the document with the added text that I had not proactively saved myself should have been preserved by those functions, shouldn't it -- or did proactively selecting 'revert changes' wipe all of that text -- i.e., all text added since the last 'normal' save?

Also, even if the text I lost isn’t in a cache, since I haven't resaved the TextEdit doc since I reopened it, is it possible that it’s still stored in a swap location (i.e., on disk)?

My understanding of ‘swaps’ is that the OS temporarily stores data on disk and restores it to memory when needed again (when the file, or that part of it, is in use again). So I wondered whether the lost text might still be in a ‘swap locker’ (so to speak) on my hard disk that might allow me to get it back.

From your reply it seems that even if it was, it might (or would) have been deleted when the TextEdit document was exited without being proactively saved in the normal way (i.e., not with 'revert changes'). Is that the case -- i.e., situation hopeless?

Thanks again.

Thanks again, VikingOSX, for that additional information. Maybe I haven't seen any sign of 'autosave' (or 'Reverting to the Last Saved' or 'versioning') because I'm using OS 10.14.3, not 10.14.6 (?)

I only thought autosave was active because of my experience seeing unsaved (by me) content preserved in certain circumstances where I wouldn't have expected the 'unsaved' text to be retained.  

In any event, what happened here is that I thought I was taking a shortcut for getting rid of all the white space that had somehow been added to the document since I had last used it. I assumed, given the time gap since I had last entered any text, that autosave had preserved everything except that white space, and that saving with 'revert changes' would just remove all the 'white space' -- and only that. 

Apparently, if 'revert changes' is selected, everything added to the document since the last 'save' actually executed by the user is wiped out. I don't know what else would explain the loss of everything in the document since the last 'save' actually executed by me because everything after that was gone. That seems odd since it suggests that either 10.14.3 doesn't in fact have 'auto-save' or saving with 'revert changes' ignores it and only looks at user-executed saves.