What would be “best practice” for allowing the user to store data for my application on his phone, using the same application?
For example, my app has a database of images+short audio. I want to allow users to expand said database by using the camera to take a photo and then save some audio along with it.
On MSDN it says
With Windows Phone OS 7.1, you can store relational data in a local database that resides in your application’s isolated storage container
But the rest of the app doesn’t need 7.1, so it would be great if I could use this database/storage on 7.0 as well.
Microsoft has done a good job of upgrading devices, so unless you have a core group of users who you know can’t upgrade for some reason, you should definitely target Windows Phone 7.1. (It’s not like Android where you probably want to use an older SDK for greater compatibility.)
I have a similar app, in that it stores a library of images, audio files and data about those resources. What I’ve chosen to do is store the images and audio by themselves and then use the built-in SQL CE database to hold metadata about the resources (i.e. file paths and file names for the images and audio files, captions for the audio files).
It’s probably possible to shove binary data into the database, but I would stick with storing it straight in isolated storage. The database is pretty fast, so it won’t hurt the performance of your app.
If you really need to support 7.0, you can serialize your metadata as XML and then write it to isolated storage. This is what I did before the 7.1 release. Data access is likely going to be faster from the database than it would be if you need to read an entire XML file into memory, then parse it into objects.