Sync between iPad and PC -- which has precedence?

Discussion in 'iPad' started by macrumorsuser10, Jun 21, 2011.

  1. macrumorsuser10 macrumors 6502

    Joined:
    Nov 18, 2010
    #1
    I'm having some potential problems with a PDF reading-application. I would like to delete it and restore it from my last iTunes checkpoint on my PC.

    The problem is that I have a lot of annotated PDFs already in the application and want to make sure the files are all kept.

    If I delete the app and then sync with iTunes on my PC, will the version on the PC get copied to my iPad, or will the absence of the application on my iPad delete the sync'ed application on my PC?
     
  2. Night Spring macrumors G5

    Night Spring

    Joined:
    Jul 17, 2008
    #2
    If you delete the app from your iPad, it'll delete all your PDF files. (it won't delete the app from your PC, but that doesn't help you, since you want to keep your files)

    Now, when you say you want to ”restore from your last checkpoint on your PC," what exactly do you mean? Did this app update to a new version recently, and you want to go back to an older version of the app? Or is the problem that you think there is some problem with the app data (like maybe one or more of your PDF files are corrupt), and you want to reset the data to an earlier state?

    Either way, it's not easy to do. You may have to export all your PDF, delete and reinstall the app, and put the files back in. Oh, and please let us know what app this is, that may give people ideas about things specific to that app that could help you.
     
  3. macrumorsuser10 thread starter macrumors 6502

    Joined:
    Nov 18, 2010
    #3
    I am using GoodReader. For some reason, in some PDFs the images do not render well or at all. The PDFs are fine when I view them on my PC with Acrobat Reader.

    I think there may be a problem with the app, and I want to try reinstalling the app. I have not added any new PDFs since my last sync, so I would just like to reinstall from the last sync. I don't think the app itself has been updated via the App Store since that sync.
     
  4. Night Spring macrumors G5

    Night Spring

    Joined:
    Jul 17, 2008
    #4
    Have you tried contacting GoodReader support? Maybe there is something about those particular PDF files that makes it difficult for GoodReader to render those images.

    Unfortunately, Apple's backup system doesn't let you restore the data app by app, so trying to restore to a previous "sync" doesn't work the way you are thinking.

    If you do decide to try reinstalling the app, you would first have to copy all your PDFs to the computer. Then delete the app from your iPad. Then you can either redownload it from the app store on the iPad, or sync it back from your computer by checking it in the apps tab of your iPad in iTunes. Then you would copy all your PDFs from the computer back into GoodReader.

    Let me know if you need clarification on any of these steps. But I'd first try contacting GoodReader support. If the problem is with the PDf files, you would be doing a lot of work for nothing if you reinstall the app.
     
  5. macrumorsuser10 thread starter macrumors 6502

    Joined:
    Nov 18, 2010
    #5

    I'm a little confused by the syncing process. I previously had an iPad 1 and then bought an iPad 2. When I synced the iPad 2 to my PC, iTunes transferred all my apps from my PC to my new iPad 2, including all the PDFs that were installed inside of GoodReader. All other applications that had their own documents (such as Keynote) also had their documents restored.

    Now, if I delete GoodReader off my iPad 2 and then sync, wouldn't all the PDFs stored with GoodReader from my last sync also be copied over from the PC to my iPad (along with GoodReader itself)?
     
  6. Night Spring macrumors G5

    Night Spring

    Joined:
    Jul 17, 2008
    #6
    No, not really.

    Syncing and restoring from backup is a different process.

    When you bought your iPad 2, what you did was restore from the backup of your iPad 1. This put all apps and their data from the iPad 1 onto your iPad 2. But you can't do this on an app-by-app basis, it's all or nothing. So if you try to restore from an earlier backup of your iPad, ALL apps' data would revert to the last backup you have on your computer, not just GoodReader.

    If you delete GoodReader off your iPad, then iPad and iTunes will interpret that as you don't want the app and its data anymore. So it will delete your data off your iPad, and won't restore that data from your PC when you sync. In fact, it will delete the data from the backup too.

    A copy of the GoodReader app will remain on your PC, but it will be just the app, without any data.

    Hope that made sense.
     
  7. mikelegacy macrumors 65816

    mikelegacy

    Joined:
    Dec 5, 2010
    Location:
    Pittsburgh, PA
    #7
    This is definitely just an app that is not functioning properly. It most likely just can't handle the files' size or something.
     
  8. macrumorsuser10 thread starter macrumors 6502

    Joined:
    Nov 18, 2010
    #8
    I just tried this with another PDF-reader application that I downloaded and found that PDFs stored with the app were recovered from my PC! Here is what I did exactly.

    1. I installed the PDF-reader app on my iPad 2 and loaded a PDF file into it via iTunes.
    2. I synced my iPad 2 with my PC and then unplugged.
    3. I deleted the app off of my iPad 2.
    4. When I plugged my iPad 2 into my PC, iTunes showed the app's icon but without the checkmark next to it, which probably reflects that it's been deleted off the iPad. I enabled the checkmark and sync'ed again.
    5. After syncing, the application is back on my iPad along with the PDF that I had loaded in step 1.

    What?
     
  9. Night Spring macrumors G5

    Night Spring

    Joined:
    Jul 17, 2008
    #9
    I've noticed that happen occasionally. For instance, I once deleted a game and reinstalled it later, and found the game level set where I last left off. All I can tell you is it's not supposed to work that way, so if you delete GoodReader, there's no guarantee it'll behave the same way.
     
  10. macrumorsuser10 thread starter macrumors 6502

    Joined:
    Nov 18, 2010
    #10
    Do you have a pointer to any information that specifically says that deleting an app and then re-sync'ing will not recover the documents inside the app?
     
  11. anjinha macrumors 604

    anjinha

    Joined:
    Oct 21, 2006
    Location:
    San Francisco, CA
    #11
    It's just how it is and it always been on the iPad, iPhone and iPod touch.
     
  12. Night Spring macrumors G5

    Night Spring

    Joined:
    Jul 17, 2008
    #12
    When you delete an app on the iPad, a warning message pops up saying "Deleting 'APP NAME' will also delete all of its data."

    I'm not sure how much clearer you can get than that.

    I also know that app data isn't stored on your PC anywhere other than the "all or nothing" backup iTunes makes of your entire iPad.

    Like I said before, occasionally, it turns out that the data is still there after you delete and reinstall an app. I suspect this happens because the "deleted" data isn't immediately overwritten. But whatever the reason why sometimes deleted app data is restored after a reinstall, that warning pop-up makes clear that Apple doesn't guarantee that the data will be preserved. So if you delete GoodReader without first copying all your PDF, then you have no guarantee that you will get them back when you reinstall it.
     
  13. macrumorsuser10 thread starter macrumors 6502

    Joined:
    Nov 18, 2010
    #13
    Apparently it turns out that this assessment is incorrect.

    On page 123 of the iPad User's Guide (pdf), it says:

    When you sync, iTunes automatically backs up any apps you download to iPad. If you delete an app on iPad, you can reinstall it if it was previously synced.

    Important: If you delete an app, the documents associated with the app are deleted from iPad, unless you reinstall the app and restore its data from a backup using iTunes.​


    So it looks like I can safely delete the app and then re-sync using iTunes, and all the documents will be recovered.
     
  14. Night Spring macrumors G5

    Night Spring

    Joined:
    Jul 17, 2008
    #14
    Note it says that in addition to reinstalling the app, you also have to restore from backup, as I underlined above. That is exacty what i've been telling you all along. iTunes won't automatically restore the data from backup, you have to manually start the restore process.
     

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