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.
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
I got an app I'm working on that uses static data from a sqlite database to do various things, While I only need read only access to the database, depending on the episode they pick from the first screen I want it to use a different database file and I want the list of available episodes to be updateable on the fly. and I got help to get the list of available episodes updated, and the proper content downloaded and stored in separate folders, So I know I could when the episode is selected delete the sql file in the documents folder and copy in the new one each time and that would work well enough for what I'm trying to do. but it seems like a bit much extra work to have to check for file, delete file, copy in new one. then open it from there each time the user wants to pick a different episode. and I don't want to put all the sql files together as that will be a bigger hassle then the first route especially if this app stays around long enough to have a long list of episodes.
so my question here is: can I get at least read-only access to an sql file that I've downloaded (or one in the bundle for testing) with out having to first copy it to the documents? and if so how would i open the file?
Can I get at least read-only access to an SQL file that I've downloaded (or one in the bundle for testing) without having to first copy it to the documents directory?
Yes. Files in the app bundle are readable (if they weren't, there would be no point in storing files in the bundle).
And if so, how would I open the file?
It's not clear what you're asking here - if you want to perform SQL queries on the file, you should use the sqlite3 library which is available on iOS.
I have a question regarding how to update local images embedded as content in the application.
My application is built using 30 images stored as "Content" (embedded in the app) for a image gallery that I have to show. Every 2 days the application check server info to see if the images have been changed in the database, in that case then I have to compare files and if any file has changed then I have to download it and update the local image.
I have read the the best way to store images for this kind of porposses is under "Library" folder of the application, but the images that comes with the app are built as "Content" (embedded)...
Any clue on the best way to do that in monotouch?
Thanks.
Resources, like images, that you bundle inside your .app becomes part of your application. Since the application is signed you cannot update (or remove) those files as it would invalidate the signature (there's also file permissions that won't allow this to happen).
note: it can work in the iOS simulator since it does not require (or check) for application signatures, however it won't works for application on devices.
What you can do is:
Bundle default images with your applications;
Download new images (when needed) and install them outside your application (in the appropriate directory);
Have your application checks if there are downloaded images (or if images needs to be downloaded) and fallback to the images that ships with your application;
You can't change any file from your app (they're read-only).
What you can do is to save the files to a read-write directory, and at runtime check if those images are there (and not then use the ones bundled with the app).
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.