SwiftUI - ProgressBar inside Live Activity

Question

I am trying to add a simple visual progress bar to my live activity on lock screen or in Dynamic Island but I can't find a way to trigger progress calculation update. Seems like neither Timer nor @State work inside of the live activity. It's weird because both native and public apps do use progress bars in activities that update more often than once a second even when apps are suspended and look super smooth.

Apple native timer app still animates smoothly when suspended

One of my favorite apps - Structured also managed to do it when suspended

I tried already even adding Lottie animations to the activity :D

Am I missing something?

Answer 1

Apparently you are not allowed to make custom progress bars in the live activity or at least I didn't find a way to do so. iOS is limiting your abilities to trigger timers, loops and any logical methods to update the progress bar. The only way I found doing it is by using a native progress bar

ProgressView(
    timerInterval: countFrom...endDate,
    countsDown: false,
    label: { EmptyView() },
    currentValueLabel: { EmptyView() }
)
.progressViewStyle(.circular)