In the WWDC 2020 session "Background execution demystified", it was mentioned that the runtime of non-discretionary Background URL Sessions (using URLSession background transfer) is influenced mainly by factors such as the App Switcher and rate limits. Based on this information, I'm curious to know if there are specific factors that similarly affect the runtime of UIApplication.shared.beginBackgroundTask(). Are there any documented constraints or system behaviors that impact how long a background task initiated by this method can run? I would appreciate any documentation or insights that could help clarify this aspect of background task management in iOS.

I am aiming to create a feature within an iOS application to backup all photos and videos from the device to a server, similar to Dropbox’s camera upload feature. Upon initiating the upload, I want to ensure the process continues even when the app moves to the background. Would utilizing Background Task Completion be the appropriate approach to maintain the upload process in the background? Furthermore, in scenarios where the background process gets interrupted and the app transitions back to the foreground, I want to resume the upload. What would be the suitable implementation to ensure the upload resumes seamlessly? Moreover, I have observed that an app named TeraBox continues its background processes for over 10 minutes after transitioning to the background. How might this prolonged background process be achieved?