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
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
Let's say an app downloads images from web while the user is browsing the app. Let's assume there are virtually unlimited images and a new image is downloaded whenever the user demands one. These images are saved to tmp directory for caching purpose. Once the user closes the app, all the images downloaded are deleted by the app.
Now, as there are unlimited images, what will happen if the user requests next image, the storage is full and the app attempts to save the image to the tmp directory?
Will the previous images be deleted by the iOS automatically to provide the space required for the new images?
OR
Will the iOS start cleaning tmp directory associated with other apps?(If yes, what happens when the storage is full again and such cleaning has already taken place for all the other apps?)
OR
Will the app crash?
If you try and save a image to disk and the disk is full then NSData's
- (BOOL)writeToURL:(NSURL *)aURL
options:(NSDataWritingOptions)mask
error:(NSError **)errorPtr
Will return NO and an error object will be assigned to the errorPtr passed into the method. This error will have a NSFileWriteOutOfSpaceError. This error is very exceptional, and by the time you get it it's safe to say the system will have already notified the user that he is running out of disk space.
Having said that, a lot can be said about cleaning after yourself. If you're not going to use a saved image resource anymore then delete it from the file-system.
Cheers!
tmp/
Use this directory to write temporary files that do not need to persist between launches of your app. Your app should remove files from this directory when they are no longer needed; however, the system may purge this directory when your app is not running.
The contents of this directory are not backed up by iTunes.
That's the only thing documented. From this I can infer that it won't purge you tmp if your app is running,but it can purge the tmp of other apps which are not running
As #InderKumarRathore says, the docs imply that the system will not delete files from your temp directory when your app is running. The docs also don't promise that the system will delete contents from other apps' temp directories to make space for you.
I would suggest coding defensively: Keep track of the oldest/least recently used files in your temp directory and delete them yourself. Preflight file saves to make sure there is enough space, and display a message to the user if there isn't enough space to save the file(s).
I am having a real hard time understanding how to embed many images and sounds in an iPhone app. When I say embed, I mean I want the images and sounds to be downloaded with the app, and some of those images will appear when the app is run. Other images are just saved in the app's disk space, so that when a user presses a button, the image or sound will be accessed and displayed or played.
I have read tutorials on using 'core data' and such, but that only seems like a way to create objects that can be used to reference such data items, or for storing small files as binary data. Can someone please tell me how in xcode I can specify a directory of images and .mp3s to be loaded onto a phone with my app, and how I can then call those media with code?
Some example code for the following would completely solve my problem:
An app is loaded onto a phone, and it contains 3 buttons. If the user presses button #1, a sound is heard. Button #2 plays a different sound, and button #3 changes a UIImageView to a different picture. (this isn't a homework assignment or something, but if I could code this example, I could do everything I need to in my app and understand the process)
Thanks!
I mean I want the images and sounds to be downloaded with the app
Simply add the images and sounds to your project. Make sure you specify (in the Add Files to Project dialog) that they are to copied into the project and that they are to be part of the target. The result will be that the images and sounds will be built into your app (in what is called its bundle, in particular the main bundle - see the NSBundle docs). You can then fetch them out, as needed, in code. For example, to fetch an image, use imageNamed:. To refer to a sound, refer to the file as a resource within the main bundle.
Other images are just saved in the app's disk space
That is a completely different matter. You will have to get the images from somewhere while the app runs. There is no way to have the user download the app and the image end up in the app's disk space: the app must populate its disk space, in real time, as the app runs. At the time the user downloads the app, the associated disk space, outside the app bundle itself, will be empty.
For images, see the responses to this question.
Sound is similar to images, but is loaded differently, this tutorial show how to load and play sounds.
For files that are saved after the app is installed, you will need to download and save those files in your code. For starters, see Apple's guide to the iOS file system
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
I am working on a Vegetable gardening application. Apart from the vegetable name and description I also have vegetable image. Currently, I have all the images in the Supported Files folder in the Xcode project.
But later on I want to update the application dynamically without having the user download a new version. When the user updates the application or downloads new data from the server that data will include the images. Can I store those images in the supporting file folder or somewhere where they can be references by just the name.
RELATED QUESTION:
I will also allow the user to take pictures of their vegetables and then write notes about the vegetables like "just planted", "about to harvest" etc. What is the recommended approach for storing pictures/photos. I can always store them in the user's photo library and then store the reference in the local database and then fetch and display the picture using the reference. The problem with that approach might be that if the user accidentally deletes the picture from the library then it will no longer be displayed in my application.
The only way I see if to store the picture in the app local database as a BLOB.
No you can't put the downloaded images with the others inside the supporting file folder. Also I would suggest you put the images inside an Images or Resources folder instead... If you want to download any data after the app is compiled, then they will not be in the bundle. It is the bundle you are referring to when talking about the Supported Files folder in Xcode. This is read only for your application.
Just to be clear, once compiled, there are no folder structures for your application, these "folders" are just groups in the Xcode project to keep things tidy.
If you download say a zip file containing a set of images, it's up to you to write them to disk after you download them. You should put these images in either the tmp, the cache or the documents directory.
But then you'll have to build your path before loading the images. You won't be able to just provide the name of the file such as:
[UIImage imageNamed:#"something.jpg"];
Because this will look in your bundle. Instead you must do something like this to load your image from the Documents directory for example.
Your challenge is that you will end up in a state where you'll have some images in the Bundle (the ones from when you uploaded your app), and the newer ones in the documents directory. You must them check the bundle first and if there is no image there, check the documents directory.
For user generated data, I suggest also saving the images in the Documents directory, and maintaining an SQLite database of the users data, so you can map an image name to an entry in the database. You don't want to save the images as BLOB because this will inevitably slow down the performance of your queries and add extra unnecessary load on the CPU to convert to UIImage and back.
You don't want to save their images to the gallery for 2 reasons, first this means you'll be saving in 2 places because keeping a reference in your database to an external image is very fragile and you're just asking for trouble, and secondly, once the image isn't under your wing, you don't control it anymore, the user will delete it at some point, if they go back to your app they expect to see it there.