iOS 9 space-saving “app slicing” disabled for now, will return in future update | Hacker News Reader

iOS 9 space-saving “app slicing” disabled for now, will return in future update

arstechnica.com

72 pointscpeterso33 comments

Interesting that iCloud backups actually upload the apps from your device rather than just noting "you had XXX app version XXX" and redownloading it from the App Store on restore.

Updating iOS via iTunes (for beta installs, restores, etc.) has the quirk of syncing apps to iTunes, and then syncing them back to the phone. This seems like a legacy annoying thing to me: why can't it just transparently re-download them? In fact, the new iOS 9 upgrade has the "delete and then re-download apps" feature for those with insufficient space for upgrade. Not to mention, there's the "purchased" tab on your device. So, this is possible!

Going further, even the prompt to "delete and then re-download apps due to insufficient space for OS upgrade" seems unnecessary, as if revealing an unimportant implementation detail. Why can't it just automatically do the right thing? I won't mind if the app is missing from my iPhone for a couple of minutes. If the reason is bandwidth, perhaps it could say "we'll do this on wi-fi only."

Similarly, I wish purchased iTunes media started working the "streaming" way, too. I don't want the TV show to take up Gbs of disk space, don't particularly care for the physical file present on my disk. Could still have an opt-in "use offline" option for those who need it.

Or are these all issues to appease people who want to feel like they "own" content (apps, media, etc.)?

I think this is a great forward-thinking feature of iOS. Some apps I have are no longer available via the app store. The only way I can retain access to them is via local copies.

That's not true. You can access the last version of any purchased app from the AppStore -> Updates -> Purchased, regardless if it is available or not on the store for you.

Tammer has the right of it, actually. There are (at least) two classes of "not on the app store," the first is as you describe, not generally available but there for legacy purposes and can be re-downloaded from the Purchased (not on this device) tab. The second is completely gone and only available if you've backed them up somewhere. There's even a modal dialogue alerting you to this fact when you have finished a restore (basically: go sync if you want certain apps that could not be downloaded back)

Unless an app has been completely removed from the AppStore by Apple (for instance, a malware app), the last available version of all apps will exist in the "Purchased" list. If an app is "completely gone", it probably has a good reason not to be there in the vast majority of cases.

> If an app is "completely gone", it probably has a good reason not to be there in the vast majority of cases.

So want to take away my right for the app I legitimately purchased and downloaded to my PC for later installation ? This cloud BS has really taken its toll.

I think there is a misunderstanding. As I remember, even apps removed by developer will appear in the "Purchased" history. So what remains is a very narrow case where you'd actually lose an application you want.

Not true, some things are retroactively removed because they do not follow new guidelines from Apple. Or they got in and they break existing rules. Those are removed completely and only can be restored by back up.

The owner can remove it, too. Marco Arment's iOS ad blocker is the most immediate example that comes to mind.

If an app is "completely gone", it probably has a good reason not to be there in the vast majority of cases.

Cold comfort to those who paid for said app.

Are you sure Arment's app does not appear in the "Purchased" history list? As I remember, unless you request a refund, it will appear there.

I have an app that I love whose owner went out of business after removing the app from the store. I purchased it for my 3G,and since then I've had to manually transfer it from iTunes, until I switched to iCloud backups which have muddled the issue for me... Anyhow it shows up in "purchased" with an "open" button if it's on the device, and (my recollection is that it) just shows up with no button and no download icon if it is not.

It is. I just tested installing it on my iPad which didn't have it installed and it showed up and installed fine from "Purchased".

But what if I don't want the latest version?

Correct, the completely gone case does not allow you to download the app any more. This can be due to copyright issues etc.

Half the time while watching Apple keynotes, I'm going "wait, it didn't do that already? Why the hell not?"

When restoring a device all apps are downloaded from the App Store, and if there's one app that's no longer available there it's not getting restored. So it's not simply "upload it all to iCloud backup"; maybe there's some kind of lookup-by-hash of something that fails when the hashed info is sliced or some such.

Makes sense to me, in the case of a user who doesn't want the latest update to a particular app.

But "you had XXX app version XXX" would cover that, no?

Well, it's what iTunes has always done.

So, if I enable bitcode it just doubles the size of my binaries currently?

It (roughly) doubles the size of the app bundle you upload to Apple. They then compile that down to create normal sized binaries, which are what are actually downloaded to the device.

Bear in mind the source->bitcode->binary process (I'm simplifying here) was previously all performed by LLVM on your computer anyway. It's just that now the final bitcode->binary step is done by Apple, to allow device-specific optimizations of the binary for the devices that are downloading it without you having to do all those device specific optimized builds yourself.

Do you know what the performance increase is of these optimized builds?

No idea. We'd need to do on-device profiling of 'plain' builds directly from XCode alongside the builds downloaded from the app store, but of course optimizations may only be possible on particular devices, and some apps would benefit more than others, so you'd have to do a huge amount of testing to track down the differences. Also Apple may be doing this due to planned advantages in the future, so testing done now might be pointless anyway.

Its just strange that Apple has not presented any actual numbers on this. Usually you'd expect them to talk about how XYZ is 90% faster, and 100x awesome and what not. It makes me think that they have something else in mind.

It's most likely so you don't have to update the binary when the next version of LLVM comes out. There are a lot of apps that don't get updated with major iOS versions and they would likely see improvement.

Conspiracy theories aside, wouldn't it take them more effort to ship a different version of LLVM for Xcode and another one that runs against bitcode?

It is not a conspiracy theory per se, I'm just skeptical of their optimization claims. In theory, sure. In practice, I'd have to see hard data.

%s/optimized/backdoor'd/g

I mean, who can tell right?

Too bad. This was going to make the 16G iPhone actually viable.

I'm running the latest iOS released this week on my 4G iPhone 4S, 1.7G still free. Granted, I don't store videos/photos (long term) that much.

The storage problems are exacerbated for the newer phones, largely because the cameras keep taking higher resolution pictures.

so apparently you had enough space to do the OS upgrade? good to know. But still, apps will be much smaller with app thinning.

I have an even better space saving feature for iOS devices - quadruple the storage. The flash storage prices have always been the biggest ripoff of iOS. And the increases of storage on the devices have not kept with the way the capacity have increased and prices have gone down.

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