In my iOS app I would like to give the possibility to save photo obtained from the iPhone camera. I'm undecided how to save these pictures and then show them to you later. From reading the Apple Documentation and other articles, I found three possible solutions:
Save image into Documents folder of app
In my app i use also core data, so i create an entity with a Transformable attributes where a can save the photos
Photo library (this feature is aviable from IOS5)
In your opinion what is the best solution among them?
First one is best, you can save image into Documents folder of app.
First it dependes on what your application does ,In your case it is more likely to use Document Directory i suppose . you can also find below guidelines useful .
Document directory have advantage of Sandboxing .
Store file path in core data and image in document directory and use them when needed.
more easy to synchronize core data and image store in Document directory . Example : deletion of image from document directory and core data .
most important , please see apple ,ios data usage guidelines , as some app got rejected because of this
https://developer.apple.com/icloud/documentation/data-storage/
http://www.chrisboyd.net/post/25806584185/icloud-and-the-new-ios-data-storage-guidelines
Your customers might complain about too much data being backed up to iCloud.
Remember to not start a big job of moving files on the main thread during app startup. This will get your app killed by the startup timer watchdog.
if you dont want icloud backup .you have two options :
1.Put your files in the Cache directory then they won't be backed up and Apple won't reject your app. However, when iOS 5 gets low on space it may delete all the files in there
2.Put files in Documents but flag them so that they are not backed up. There's a technote (QA1719) on how to do this. This only works in iOS 5.0.1 and later
you can also see this link for more
http://iphoneincubator.com/blog/data-management/local-file-storage-in-ios-5
Related
Currently i was saving my application data (Media) to the CacheDirectory i.e
/var/mobile/Applications/BEAFC76C-C450-4A3A-9765-A0385A9580F3/Library/Caches
and things were going fine. But recently i got a bug report that the application data has been deleted. When i searched over it, i got this Apple Doc. According to it, DocumentsDirectory should be the ideal place to store the User/Application data.
Put user data in the /Documents/. User data is any
data that cannot be recreated by your app, such as user documents and
other user-generated content.
And Cache should not be used to store the User Data that could not be reproduced by the application.
Put data cache files in the /Library/Caches
directory. Examples of files you should put in this directory include
(but are not limited to) database cache files and downloadable
content, such as that used by magazine, newspaper, and map apps. Your
app should be able to gracefully handle situations where cached data
is deleted by the system to free up disk space.
What should be the ideal place to store it.
EDIT:
I have an application that allows user to store Videos and Photos in the application. For that i used CacheDirectory. But i am getting bug reports that the Data (Videos/Photos) is getting deleted. What conclusion i draw is that the data is being getting delete by the Device itself in order to provide space.
Secondly i also wanna give the iTunes sharing function. So only the particular files has to be stored in the DocumentsDirectory. Some files can never be exposed and some has has to be shared. What should be the ideal way to store the files.
Use Documents (NSDocumentDirectory) for files you wish to share via iTunes.
Use Application Support (NSApplicationSupportDirectory) for files you wish to hide from the user but still be backed up and never deleted by the OS.
Starting iOS 5, Apple says that it's no longer a good thing to save all kind of files in Documents Directory - if you do that, your app will be rejected for sure because this folder is backed up to iTunes & iCloud, unless otherwise specified.
It says that we should save files into Caches or Tmp Directory - these won't be backed up, but it's not a good thing to do because files from these directories can disappear if low memory happens.
So I think the best think to do is to save the important files that you need all the time in your app into Documents Directory and mark them not to be backed up, like this.
Library/Application Support Folder is the folder you should be using.
This directory doesn't always exist, and thus you may need to create it.
You can enable or disable whether you want to backup this data with iTunes or not.
This data is not accessible even if you enable file sharing. Only data that you put in Document directory would be shared with iTunes sharing, so you can still protect your data and get it backed up as well. Apple's documentation
In my app user will have a list of items, each item will have a thumbnail,the thumbnails are downloaded from the net, so i want to save the images in the app directory, so that the app won't download thumbnails every time, now i am saving images in NSLibraryDirectory, and there are many directories available like NSDocumentDirectory,NSApplicationSupportDirectory.. those images will be downloaded if they are not present in the NSLibraryDirectory.My question is which directory is the correct place to save these thumbnail images so the user need not download the images every time. Previously i used NSDocumentLibrary but i have read that those will be backed up by iCloud and apple could reject the app for that. So, i have changed to NSLibraryDirectory and everything is working fine. Is it okay to do so. Any better way to store images like that.Thank you
Here is all about this:
https://developer.apple.com/library/ios/documentation/FileManagement/Conceptual/FileSystemProgrammingGuide/FileSystemOverview/FileSystemOverview.html
I prefer to store thumbnails in temporary directory which system clears automatically. I also wrote class which is responsible for cache files in directory you set.
http://github.com/tomkowz/TSFileCache
it's downloading and retrieve images memory waste. better use: https://github.com/nicklockwood/AsyncImageView
my app has been rejected due to iCloud Storage Restrictions. (2.23).
There are lots of questions for this situation, but i am still not sure why my app has been rejected.. Here are my suspects:
1- My app downloads pdf files and images for letting users see on "offline" mode when a user selects a row from a tableview. I've set my download folder as "Documents/privateDownloads" and set the folder (and files inside) url flags as "do not backup"
2- My app also has a 2Mb. "preload.json" file, which my app reads the file at first launch and preloads into the database only at first launch (with a progress hud showing the progress of importing data). I haven't set the "preload.json" file as "do not backup".I just drag dropped the file into "Supporting Files" group in Xcode.
My guess is the problem lies in the 2nd suspect, but i've also read that i should move the "privateDownloads" folder into "Application Support" Folder instead of Documents folder.
i always stored my offline files on nsurl cache for a very long time (technically forever), but this time i've decided to do like this.
thanks for reading and helping.
Edit: there is a note from app store for rejection reason:
"In particular, we found that on launch and/or content download, your
app stores 3.6MB"
When i control this issue, this is happening after my application "preloads" the data. But what i really don't get it is, i am storing this preloaded data in core data. So yes, i want this data to be backed up in iCloud?!
To solve the issue of your seed data being too large, you might split your Core Data stack in two separate stores - one which stores the user data and is backed up to iCloud. And a second one which stores the seeded data imported from your JSON. This store could then be excluded from iCloud backup via the "do not backup"-flags.
Another recommended way would be to ship a pre-populated store like described in this article on objc.io. Since you mentioned your preload.json is several MB, this would be even more desirable to pre-generate the store once than on every device on initial app startup. And you could apply the required file attributes for not backing it up more easily.
The issue won't have anything to do with your preload.json file. If that's included in your app distribution, it is part of the app and you don't need to do anything different with it.
I would suspect that the reviewer didn't notice you were setting the 'do not backup' flag on files you've added to the Documents/privateDownloads folder, or that you have a bug and the flag isn't being set at all. It is safer, if you're able, to store those kinds of files in a /Library/Caches sub directory. Then you don't need to worry about the flag.
I am trying to code a hard disk based restore function into an existing demo Photo Application for iOS devices. The idea is to allow users to restore the last applied effects and all, even after restarting the application/unexpected crash etc.
I am saving one image file (the latest effects applied to it) into the NSCachesDirectory:
NSData* data = UIImagePNGRepresentation(image);
[data writeToFile:[self getFileAtIndex:getPath] atomically:YES];
On going to the recover option, the file saved at this path is recovered using:
image = [[UIImage imageWithContentsOfFile:[self getFileAtIndex:getPath]]retain];
The code is working fine in my test device (iPhone 4s). But somehow I doubt if this is the best practice for coding a restore function.
Moving into a real world app, if things were stored in NSCachesDirectory, do you think it will be backed up into iCloud? Is there any possibility of a conflict with other apps?
How exactly is NSCachesDirectory directory managed for multiple apps accessing it simultaneously?
I would like to know the best practice for doing this.
Please help/comment.
As Mr. Bonjour mentioned in the comment, on iOS, every app has its separate file system, so there can never be any conflict with other apps.
Caches directory is not backed up on iCloud and you shouldn't rely on files in caches directory to persist across launches. You should use caches directory for temporary files only. If you allow restore only during one session, then using caches directory is fine, but if you want to allow restore across multiple launches, you should store them in library/documents directory. But be aware that Apple has a strict review policy for storing files in Documents directory since it takes up space on user's cloud storage.
I need to store some data files for my blackberry app. These are usually small png files that I download and store locally for performance reasons. Also I need to store an xml file locally.
My question is where are these files supposed to be saved on a blackberry? Is there such a thing as an application's home folder or settings folder in the blackberry filesystem?
What would be the path to such a folder?
This is for blackberry os 4.7 or later.
Thanks!
If it's not a huge amount of data (and by the sounds of it, it's not), take a look at the PersistentStore mechanism. You can store many types of data including native types (String, Integer, etc.) and even byte[] data (for images) using PersistentContent. The nice thing about PersistentStore is that it doesn't require any sort of filesystem access -- it doesn't leave files hanging around -- and if you include a custom class in the persistent store for your app (even a simple subclass of an existing persistible class such as Hashtable), it will automatically delete your persisted data if the app is deleted.
There's no official home folder for your application. In blackberry you can basically read/write just about anything/anywhere (well, you might get a SecurityException/IOException if you'll try do change some files).
You can write to the SDCard/Internal memory using the paths described here.
If you're worried about someone seeing and altering your data there's not much you can do except setting your files and directories as hidden using FileConnection.setHidden(true) but this is very lame since they can still be seen even from the native BlackBerry file browser if the user chooses to show hidden files from the menu.
Edit: You could of course encrypt/decrypt your data but this won't prevent someone from deleting it.