I have an app that I want to update the badge icon weekly. I see that at least pre iOS7, UILocalNotification could only set the badge icon to a specific number like
someLocalNotification.applicationIconBadgeNumber = 42;
But I want my app to load in the background lets say every sunday, do a calculation based to get the difference between the current date and some start date, and update the badge number accordingly.
UILocalNotification can't do this apparently. It looks like push notifications can, but I don't have a server component for this app, so using that as a workaround wouldn't work, and I'm not sure Apple would like it anyway.
I know there is some background app refresh updates in iOS7, but I'm not sure if they would work in this situation.
TLDR: How do I update a badge icon in iOS7 that requires a bit of calculation to get the correct number, on a weekly basis (or any arbitrarily long time basis)? And I want to do this background updating without a server component.