Apple Watch is designed to keep information flowing from your iPhone to your wrist. The convenience of not looking at your phone is sometimes replaced by a barrage of notifications on the watch. Apps are set by default to "mirror iPhone alerts", which means any notifications appearing on the iPhone are delivered to Apple Watch. If you find that too many alerts are popping up, watchOS notifications can be customized or disabled.
Taking secret screenshots on Snapchat is a cat and mouse game. Every time a users discover a new workaround, Snapchat finds a way to keep Snaps secure. The basic idea is that capturing a screenshot triggers a notification to the other party, making sure that communications stay private. Despite their best efforts, it remains possible to secretly screenshot a Snap. Let this also be a warning to anyone sharing with Snapchat: the privacy of communications in any app depends on both parties keeping their side of the deal.
Battery management features on iOS have improved greatly over the past few years. iPhones manage their own charging to optimize battery life, sometimes delaying a full charge based on usage patterns. The iPhone may display a battery percentage while charging, however there's no audible alert when charging has completed. For anyone interested in knowing exactly when their device has finished charging, Apple offers the Shortcuts app.
Notifications from your various apps vary greatly in importance and frequency, and this is something Apple has taken note of and tried to address with a variety of management options. While in the early years you could simply turn notifications on or off, you can now manage notifications by individual app. You can turn notifications off for a particular app altogether, or you can turn off the sounds or badges and decide whether you want them to show up on the Lock Screen or Notification Center or as a banners. iOS 15 introduces a new management tool - the Notification Summary.
All wireless providers deliver government-issued Wireless Emergency Alerts (WEA) to iPhone owners on their networks. The capability to receive these alerts was added with a Carrier Settings Update in 2013. There are four types of alerts, three of which iPhone owners can turn off.