iOS 17.4 introduces a small but useful change for the Clock app's Stopwatch function, adding the timer to Apple's Live Activities feature. When activated through the Clock app, the Stopwatch will now show up both in the Dynamic Island and on the Lock Screen.

The ‌Dynamic Island‌ shows a small to-the-second timer, and the Lock Screen shows the full Stopwatch timer when the screen is being looked at. Pressing into the ‌Dynamic Island‌ shows options for pausing the Stopwatch or starting a new lap, with these controls also on the Lock Screen. After the Stopwatch is paused, swiping on it from the Lock Screen or tapping on the "X" in ‌Dynamic Island‌ will clear it.

Timers have worked with Live Activities since the feature launched with iOS 16, but the Stopwatch could only be viewed in the Clock app. The addition of Live Activities support will prevent users from activating the timer and then forgetting about it.

Source: Macrumors