Don't panic, Mac users -- just because Apple only released iOS 11.4 at first doesn't mean it has forgotten about you. The company has posted a macOS High Sierra 10.13.5 update that supports Messages in iCloud, providing both more consistent chat syncing across your Apple-made devices as well as a way to free up space. You can delete a message on your iMac and expect it to vanish on your iPhone, or set up a new MacBook and access your entire conversation history.