Keeping mobile devices powered is a persistent challenge. As iOS tries to do more and more for you, features like background tasks, Location Services, iCloud syncing, and Background App Refresh can strain a battery. Fortunately, iOS offers some tools that can extend your battery life.
In Settings > Battery, under Battery Usage By App, apps are sorted by how much power they’ve used, but apps near the top aren’t necessarily wasteful. If you use an app often, it naturally uses more battery.