I'm planning on having a generated file be stored in the App/Documents file for my app. I want this file to be unique across installations so that if a user has an iPad and an iPhone they will have two different versions of the file.
I've been reading the specification(https://developer.apple.com/library/ios/documentation/FileManagement/Conceptual/FileSystemProgrammingGuide/FileSystemOverview/FileSystemOverview.html) and am particularly concerned about this line.
Use this directory to store critical user documents and app data files. Critical data is any data that cannot be recreated by your app, such as user-generated content.
The contents of this directory can be made available to the user through file sharing. The contents of this directory are backed up by iTunes.
My question is will the files be backed up to the users account in the cloud?
yes it is. The Documents Directory is a key location in an app. which means that if you put anything in the documents, it will back up to itunes(if the user wants to). so even if you generated a unique file across installations, it will re-download the EXACT file to a new system if they downloaded it previously. so unique files in the DOCUMENTS will not be possible (unless a person uses a diffrent apple account on every one of his devices. which is not likely.)
Related
I'm coding a small app to manage a guest list. To stock this list, I use a .plist file (It is an array -> .plist is practical.) I wanted to have the possibility of editing this file with my computer (I have to fill it with 1000 people or more...) Have some one a solution to make a file accessible with a Mac (With iTunes I suppose) ? (as Stop Motion : You can take the videos you have made in iTunes).
Thanks !
According to apple doc:
File-Sharing Support File-sharing support lets apps make user data files available in iTunes 9.1 and later. An app that declares its
support for file sharing makes the contents of its /Documents
directory available to the user. The user can then move files in and
out of this directory as needed from iTunes. This feature does not
allow your app to share files with other apps on the same device; that
behavior requires the pasteboard or a document interaction controller
object.
To enable file sharing for your app, do the following:
Add the UIFileSharingEnabled key to your app’s Info.plist file, and set the value of the key to YES. (The actual key name is
"Application supports iTunes file sharing")
Put whatever files you want to share in your app’s Documents directory.
When the device is plugged into the user’s computer, iTunes displays a File Sharing section in the Apps tab of the selected
device.
The user can add files to this directory or move files to the desktop.
Apps that support file sharing should be able to recognize when files
have been added to the Documents directory and respond appropriately.
For example, your app might make the contents of any new files
available from its interface. You should never present the user with
the list of files in this directory and ask them to decide what to do
with those files.
For additional information about the UIFileSharingEnabled key, see
Information Property List Key Reference.
I want to keep an apps documents directory that contains sqlite using core data files in sync across users' devices. The sqlite files are the only files in the apps documents directory and simply need to be common to all users' devices
I've tried zipping up the sqlite files to send by email, which works with iTunes file sharing but is not suitable for my needs as it can expose the files to other users' devices.
I've tried using app groups to keep the directory common across devices http://blog.sam-oakley.co.uk/post/92323630293/sharing-core-data-between-app-and-extension-in-ios,
and
Accessing Core Data SQL Database in iOS 8 Extension (Sharing Data Between App and Widget Extension) but that simply did not share the directory across devices for me.
I've sent the file to parse, but pulling them down and reconfiguring the data was the problem there.
I've tried using iCloud and even the Apple engineer gave up on that one.
What I'm after is the simplicity of file sharing through iTunes (being able to replace the sqlite files) with a bit more finesse and without the need to plug in the device.
Some considerations
The whole model can be synced in one go
Data does not need constant syncing facilities, a manual sync option would suffice.
I was under the impression that iCloud only worked with UIDocument files.
How about other types?
Also if my user's files get uploaded into the cloud, can he use those files with all his devices if my app is universal?
According to Apple's File System Programming Guide,
Handle support files—files your application downloads or generates and
can recreate as needed—in one of two ways:
In iOS 5.0 and earlier, put support files in the
/Library/Caches directory to prevent them from
being backed up
In iOS 5.0.1 and later, put support files in the
/Library/Application Support directory and apply
the com.apple.MobileBackup extended attribute to them. This
attribute prevents the files from being backed up to iTunes or
iCloud. If you have a large number of support files, you may store
them in a custom subdirectory and apply the extended attribute to
just the directory.
iCloud does back up of the things under Library also.
Ans YES of course if user's files get uploaded into the cloud, then he can use those files with all his devices if the app is universal as iCloud is intended to be the invisible magic that glues your iPhone, iPad and Mac (if you use one) together.
I'm trying to store analytics data that is saved locally about a user's actions so it can be uploaded later when the user has an internet connection. I'd like the data to be stored locally and not deleted between subsequent opens of the app under normal circumstances. I do not want the data to be synced to iCloud. I'd also ideally like the data to be preserved between updates. It's fine if the data gets deleted in cases of low space.
I'm getting different answers from different sources about where to store the data- either in NSCachesDirectory or NSLibraryDirectory. Note NSCachesDirectory is a subdirectory of NSLibraryDirectory, eg. the filesystem looks like Application_Home/Library/Caches/.
According to the official documentation: http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/PerformanceTuning/PerformanceTuning.html#//apple_ref/doc/uid/TP40007072-CH8-SW9 implies I should use NSCachesDirectory to store the data and it is not deleted under most circumstances. It also implies NSLibraryDirectory is synced to iCloud.
According to these answers: How can I get a writable path on the iPhone?, https://stackoverflow.com/a/5444762/340520/, When are files from NSCachesDirectory removed?, NSCachesDirectory is not preserved between app updates and claims that I must constantly recreate the NSCachesDirectory. The first answer also implies NSLibraryDirectory is the best place to store the data. However those answers are two years old.
According to the documentation and this answer: http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/PerformanceTuning/PerformanceTuning.html#//apple_ref/doc/uid/TP40007072-CH8-SW10, https://stackoverflow.com/a/8830746/340520, NSCachesDirectory ARE preserved between app updates.
Localytics' iOS SDK stores their data in NSCachesDirectory: https://github.com/twobitlabs/Localytics-iOS/blob/master/src/LocalyticsDatabase.m
Mixpanel's iOS SDK stores their data in NSLibraryDirectory: https://github.com/mixpanel/mixpanel-iphone/blob/master/Mixpanel/Mixpanel.m
Between all these sources, I've been leaning toward using NSCachesDirectory, but I'm not confident that the data won't get regularly deleted under some circumstances.
NSCachesDirectory is the wrong place to store persistent information that you will need across app starts or even device re-starts.
To prove my point try this ...
Get a iPhone device that has only 8GB disk space.
Use your app to write a file in the NSCachesDirectory.
Start downloading random apps to fill up the disk space. Very soon you will see the Storage limit dialog shown by the OS.
Now just re-start your phone, start the app and see if you can find your file that you wrote.
If the first time you find the file, try the experiment again and you will find your file missing. During the device startup, if you see the device logs you will notice logs indicating purging directory to make space etc.
Use NSCachesDirectory to store information you can keep downloading from your server. Not information that you need to upload to your server.
The Caches directory should only be used for files that your app can easily replace if they are deleted. The Caches directory is may or may not be purged during an app update and possibly if the device runs out of storage space. Only use this for temporary files or files you can easily replace.
My first choice would be the Library/Application Support directory (NSApplicationSupportDirectory). Please note that this directory is not created by default. Your app must create it on first startup. This path is kept during app updates (like most of the app sandbox) and it is backed up via iTunes (or iCloud) device backup.
I think the best place is Library/Application Support (NSApplicationSupportDirectory) refer How do I prevent files from being backed up to iCloud and iTunes? for details.
When a new upgrade is released and installed on iOS, which folders / files are left untouched by the upgrade process? There are several folders; Library, Caches, Preferences, Documents.
Normally Application Support Directory is not created by default. What happen to AS folder during upgrade?
I learn that all data in Documents folder will copy to iTunes or iCloud by default. Is that true?
If I create my own CoreData db to persist, where should I keep?
Your best bet is to read the first half (which pertained to iOS) of this document from Apple:
In my experience, I put Core Data db in Documents folder if the iTunes File Sharing feature was not enabled on your app. Otherwise create a folder in the Library folder called Application Support or anything name, etc. With iTunes File Sharing enabled, user can accidentally delete any files in the Documents folder.
During the upgrade, the contents of Library and Documents folder are retained.