Storing JSON Data locally in iOS Objective-C

Hello, Community! I'm working on an app that displays feed like twitter, Instagram, facebook. On the first launch, the app fetches a list of videos on displayed in a tableView. I want the data to be persisted locally on the user's phone so that the last fetched data would always be on the screen even when the user isn't connected to the internet just like the apps listed above. Also to synch the data so that on next request only updated content in fetched from the service. I don't know where to start from. Please, I need detailed technical explanations on how I should do this (in the scope of iOS Objective-C). Or if there is a tutorial, course on how to do this or say an open source library, I would like to know.