12 ms·

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

72 points by cpeterso 11y ago

tobias3 11y ago
So, if I enable bitcode it just doubles the size of my binaries currently?
- simonh 11y ago
  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.
  - ksk 11y ago
    Do you know what the performance increase is of these optimized builds?
    - simonh 11y ago
      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.
      - ksk 11y ago
        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.
        Glide 11y ago
        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?
        ksk 11y ago
        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.
    - diakritikal 11y ago
      %s/optimized/backdoor'd/g I mean, who can tell right?
kalleboo 11y ago
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.
- m_eiman 11y ago
  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.
- TazeTSchnitzel 11y ago
  Well, it's what iTunes has always done.
- lpsz 11y ago
  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.)?
  - tammer 11y ago
    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.
venomsnake 11y ago
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.
rsl7 11y ago
Too bad. This was going to make the 16G iPhone actually viable.
- caio1982 11y ago
  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.
  - omni 11y ago
    The storage problems are exacerbated for the newer phones, largely because the cameras keep taking higher resolution pictures.
  - rsl7 11y ago
    so apparently you had enough space to do the OS upgrade? good to know. But still, apps will be much smaller with app thinning.

72 points by cpeterso 11y ago

tobias3 11y ago

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

simonh 11y ago
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.
- ksk 11y ago
  Do you know what the performance increase is of these optimized builds?
  - simonh 11y ago
    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.
    - ksk 11y ago
      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.
      - Glide 11y ago
        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?
        ksk 11y ago
        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.
  - diakritikal 11y ago
    %s/optimized/backdoor'd/g I mean, who can tell right?

kalleboo 11y ago

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.

m_eiman 11y ago
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.
TazeTSchnitzel 11y ago
Well, it's what iTunes has always done.
lpsz 11y ago
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.)?
- tammer 11y ago
  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.

venomsnake 11y ago

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.

rsl7 11y ago

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

caio1982 11y ago
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.
- omni 11y ago
  The storage problems are exacerbated for the newer phones, largely because the cameras keep taking higher resolution pictures.
- rsl7 11y ago
  so apparently you had enough space to do the OS upgrade? good to know. But still, apps will be much smaller with app thinning.