All your files in the cloud
Learn the differences between iCloud Drive on macOS and iOS
iCloud Drive is more frugal on iOS devices, preferring to store the majority of your assets in the cloud unless they’ve been used recently – and downloading them only when requested. You can access your assets through the Files app, where you can identify any that aren’t stored locally by the cloud icon that overlays the top-right corner of their thumbnails in icon view, or near the right end of their rows when list view is displayed.
Again, if you need to use any of these when you’re going to be offline, download them first, either by tapping them here or opening them in the appropriate app.
Photos and videos you put in iCloud can take up a lot of space. We’ll talk more about this later, but if an iOS device’s free space is low, you can recover space: go to Settings > Photos and tap Optimize [iPhone/iPad] Storage. Your device will then store the full-quality versions in iCloud, and lower-resolution previews locally, starting with your least used items. The masters are downloaded when you edit them, or open them in another app.
Clicking iCloud Drive in Finder’s sidebar reveals the files and folders stored in your iCloud account. They are automatically copied to your Mac, so even if you lose your internet connection you can still use them.
If you’ve upgraded to a 2TB account, you may have more space online than locally, in which case syncing and saving to iCloud from several devices can completely fill your Mac’s drive. To avoid this, go to System Preferences’ iCloud pane and click Options next to iCloud Drive. Make sure Optimize Mac Storage is ticked. iCloud will then intelligently free up space occupied by items that you haven’t used in a while from this Mac. Don’t worry, it’ll leave copies in the cloud, and the files’ icons will still appear in Finder.
Naturally, you won’t be able to use those offloaded files when you have no internet connection, so if you know you’re going to need one when you’re on the move, download it by clicking the cloud icon beside its name, or, if you need a whole folder, the same icon beside the folder one level up.