Retrieve asset metadata or request full asset content.
You fetch assets to begin working with them. Use the class methods listed in Fetching Assets to retrieve one or more
PHAsset instances representing the assets you want to display or edit. For example, to fetch all the assets in an asset collection (such as an album or moment), use the
fetch method. Each fetch method takes a
PHFetch parameter that you use to specify the assets to retrieve and how to sort them.