I've built an application where sometimes views fetch data after a specific time. What would be a good indicator for how long it takes until the view will update its data again? I came up with an arc that grows from 0 to 360 degrees, but I wonder if there are other solutions.
An arc is definitely one way to do this, but I would use it as a countdown so it reduces from 360° to zero, anti-clockwise. The three states illustrated here are start, two-thirds-done and about-to-refresh:
I've included a "reload" symbol here as that's a useful way of indicating what the control is showing; the control could be used as a button for an instant refresh.
(Apple currently does something similar — in reverse — to indicate download progress during updates.)