Clearing iOS App Data

What bothers me is that on Mac, even deleting an app doesn't delete its data.

@Fahad Yeah, I don’t know why Apple hasn’t added an easy way to uninstall sandboxed apps. At least on the Mac you can easily go in and delete the folders if you want.

While we're on the topic, JUST in case there are any Apple people lurking, can we ALSO get the app's iPhone/iPad Storage page linked to the app's Settings > Apps > entry too? Such a hassle having to wait for Settings > General > iDevice Storage to load, before I can get to an app I KNOW I want to offload, or just want to see how much storage THAT app is using. I submitted a bug/Feature Request to Apple on this ages ago… no response.

On macOS I still use AppDelete from the late Reggie Ashworth. One of my few Intel-only apps.

Though for App Store apps I open Launchpad, hold Option, hit the X. The only time I use Launchpad.

This has been an area where Linux and Windows mog macOS. Most package managers differentiate between "remove" a program and "purge" (remove related data, settings, etc.). Windows Add/Remove program is also straightforward to use but I know none of the details.

Android has had both of these options ("clear storage", "clear cache") in the app management settings since forever. It breaks down the storage used by "App size", "User data", and "Cache". I assume the "clear storage" button deletes both user data and cache, since there's not much point to keeping a cache if you're effectively resetting the app by deleting all the user data.

Probably because normal people don’t know what a cache is.

Deleting an app is more obvious and clear and is pretty rare.

Also, apps like X maybe shouldn’t have 3GB caches.

@Someone else Twitter is a bad example because it does have its own button to clear the cache. (But I also think it would be more user friendly to have a standard system way to clear the caches so that users don’t have to learn the particulars of each app.) The problem is the apps that don’t have cache management, so I view them as less trustworthy, yet those are the ones that the user has to rely on being able to get their data back into after deleting the whole app. iOS didn’t actually solve the problem for normal users by not having the button and not letting advanced users access the folder directly. It’s just ignoring that the problem exists.

To add insult to injury, most of these apps (X of course, but also MS Teams*, and DS audio which is the way by which I access the music on my Synology NAS), while they do feature an ad-hoc system to clear their cache, that system proudly tells you of the 10s of MBs of space freed… but according to iOS these apps still keep 100s of MBs of data, so it's not really any better that apps that don't even offer that option (like Patreon): I still need to nuke and redownload them to recover the space. Bluesky does seem to be on the level in that area.

*oddly enough for Teams this is offered in the settings app, and then requires you to kill the app, and the next launch will cause the purge. Not a good UX I'd argue.

I think that depending on the app, clearing the cache could really mean wildly different things, and would end up having plenty of unintended consequences making lots of users (and therefore developers) sad.

@Christopher Could you be more specific? Apps are supposed to be written with the understanding the OS can purge the cache whenever it wants to.

> Apps are supposed to be written with the understanding the OS can purge the cache whenever it wants to.

Exactly, and when everything works as intended (and I’m not sure it does) the system should free up space as needed by purging on its own. Nothing we _should_ be concerning ourselves with.
If the app were to put its cached data in the wrong place, of course, all this is useless.

@Pit Yeah, the automatic purging doesn’t work properly. There’s no reason to believe it ever will (even first-party apps like Messages and Photos don’t auto-purge correctly) so Apple should add a button to at least let users step in when necessary.

@Michael, I think that clearing caches should be automatic at the OS level — if the app puts those items in a cache folder, that is. (https://developer.apple.com/documentation/foundation/url/cachesdirectory) — so really, when running ‘low’ on space, the OS should be doing it for us.

If the app itself decides to not use those cache directories, that’s kind of a different issue, and an OS-level ‘clear cache’ button wouldn’t help in that case, anyway.

I think caches shouldn’t be something exposed to mainstream users — even web browsers now no longer have a ‘clear cache’ button — it’s a difficult concept to explain to grandpa. There’s something final and clear, and importantly, simple… about deleting everything and starting over. (Apple of course assumes infinite internet bandwidth)

@Someone else My point is that the common case seems to be that the app does use the right folder but iOS doesn’t clear it. Safari does have various manual controls for clearing caches.

I don’t think the caches directory is ever cleared on Mac by the OS? Just not included in backups.

> Apps are supposed to be written with the understanding the OS can purge the cache whenever it wants to.

I can’t remember all the details but I think the old docs said caches would only be cleared if the device was low on disk space but never while the app is running.

Devs should put a clear cache button if they know their cache can balloon and/or auto prune it - don’t rely on the OS. Also devs out there don’t use the caches directory if you really want to write a temporary file (they are similar but different). And don’t use SwiftUI. And stop vibe coding.

I was recently wondering why occupied storage space on my iPhone was 20 GB less than I remembered. Then realised it is the effect of restoring from backup after battery replacement.

@Michael, I agree… if Apple’s not clearing caches, then that’s a real annoying problem, and it should be fixed, or they should share the reason it’s not.

But taking a step back: do we actually know that apps are using their purgable cache folder properly? (maybe we do)

I could certainly imagine a lot of apps deciding that their cached data are more important than other app’s, and so don’t use the OS cache folders… and maying Apple’s actually doing what they say they’ll do (they’re very stingy about shared resources in other aspects, after all) and were pointing at the wrong thing.

I guess a manual ‘delete cache’ button would make more obvious who is to blame here.

@Someone else - Not sure if something has changed in recent years but the old Documentation states the following about Caches:

"Use this directory to write any app-specific support files that your app can re-create easily. Your app is generally responsible for managing the contents of this directory and for adding and deleting files as needed.
In iOS 2.2 and later, the contents of this directory are not backed up by iTunes or iCloud. In addition, the system removes files in this directory during a full restoration of the device.
In iOS 5.0 and later, the system may delete the Caches directory on rare occasions when the system is very low on disk space. This will never occur while an app is running. However, be aware that restoring from backup is not necessarily the only condition under which the Caches directory can be erased."

https://developer.apple.com/library/archive/documentation/FileManagement/Conceptual/FileSystemProgrammingGuide/FileSystemOverview/FileSystemOverview.html#//apple_ref/doc/uid/TP40010672-CH2-SW2

Apple basically reserves the right to clear caches but does not do so...very often. They always said that. On Mac I don't think they ever delete them as I mentioned previously. Temporary files != Caches directory. I believe temporary files will actually get cleaned up by the OS on a regular basis - though they also advise developers to clean up temporary files themselves. I'm not sure where the expectation to have the OS clear your caches came from.

It does suck that developers don't do the right thing often and let their caches balloon. Like I could see storing autofill history stuff in Caches - generally not super important and shouldn't be included in a backup but you don't want to just chuck it every time your app quits either. If there was a general purpose "Delete Caches button" I agree with your previous post actually -- users would just press it without understanding what they are deleting and it means different things for different apps. Devs should design their apps properly in their own Settings (e.g., "Clear Cookies") to clear their caches. If it seems inappropriate to have a button in your Settings to clear what you are caching you must prune your caches or maybe you should be writing temporary files instead.

@ObjC4Life Thanks for finding the docs. In many cases, I think it’s WebKit that’s creating the cache files, rather than the app itself directly.