Background Local cache update

First of all, App Review handles rules on a case by case basis, and usually will refrain from commenting on apps unless they are under review. So, for a final answer, you will need to submit your app. That said, these are my educated opinions.

Although this is an off label use for a Notification Service Extension which is meant to be used for modifying content in newly delivered notifications, there are no strict rules for what you can do within the limits of an extension process. The process is short lived (30 seconds), memory restrained (24 MB), and bound by a number of sandbox rules that limit the abuse it can inflict on a user's device. The OS itself will enforce the rules, up to and including deciding to not launch the extension if it historically has been terminated for constantly crashing and/or being terminated due to not properly handling the constraints.

Also keep in mind that these notifications have to be visible, and cannot be silent notifications. If you wanted to use silent notifications then you would be using the specific API designed for pushing background updates to your App. While this is an API specifically designed for what you want to do, you may want to make sure that the iOS Background Execution Limits would be suitable for your use case.

Argun Tekant /  WWDR Engineering / Core Technologies

@Engineer Thanks for your explanation. As you suggested https://forums.developer.apple.com/forums/thread/685525 for my use case, but on this thread I have not found any way to handle updates when the app is killed the user. I know as per apple guidelines this user choice is strongly respected and we can not do anything, but do we have any recent updated in WWDC25.

What I mentioned is the current state of things. There isn't anything else introduced about this at WWDC25.