Updating iOS badge without push notifications

I have seen a few todo apps that update their app badges at midnight, always showing the correct number of due tasks. They do this without the use of Push Notifications - so my question is: how do they do this? Do they use local notifications - if so, do these get called when the device is turned off? I'm a little confused and would appreciate some input.

Solution 1:

Try this

[[UIApplication sharedApplication] setApplicationIconBadgeNumber:1];

To do this through local notifications you have to set the value in applicationIconBadgeNumber

UILocalNotification *localNotification = [[UILocalNotification alloc] init];
localNotification.applicationIconBadgeNumber = 1;// set here the value of badge

Solution 2:

And for everyone using new and shiny Swift:

UIApplication.sharedApplication().applicationIconBadgeNumber = someNumber

Swift 3:

UIApplication.shared.applicationIconBadgeNumber = someNumber

Solution 3:

Since iOS 4.0 you can fire local notifications on all devices that run at least iOS 4.0. Look into the UILocalNotification class, it allows you to set the badge at midnight without having your app running.