My application is downloading data from web such as JSON, pictures, e.t.c. When installed the amount of data is supposed to be more than 50mb.
It will be expensive for those who use 3G connection. I guess my application needs to find out what is the type of the internet connection, I was told that Apple has it's own requirements for downloads, but I couldn't find any useful information from internet.
Besides that my app gives an option to download wallpaper to pictures gallery, and I guess I need to check for the connection type at this point, too?
I presume from your other question that you've discovered Reachability, from which you can determine how you're connected to the Internet.
And in answer to your other question, yes, it's reported that Apple discourages apps that download too much data over cellular connections. On Avoiding iPhone App Rejection at mobileorchard.com, they suggest:
If your app downloads data over the cellular network, ensure you do not use too much bandwidth. How much is too much? Well, there isn’t an exact number, but a tech support person from Apple advised me to not exceed 4.5 meg of data per 5 minutes of activity. You can test your app’s usage by going into your iPhone settings, choosing the General->Usage menu and clearing the stats. Then run your app for 5 minutes, return to this screen and see what the stats say. Also, to get the most accurate numbers, you should turn off any other network activity on your phone while you run the test (such as Email or MobileMe updates).
I've seen this cellular bandwidth limit of 4.5 mb per five minutes of activity sited elsewhere, too, though not in any formal Apple guidelines (such as their App Store Guidelines).
