Previously I mentioned a nice objective-c based open source library that includes many different styles of progress indicators called M13ProgressSuite.
Here’s an open source Swift based component allowing you to create customizable progress indicators in Swift called KYCircularProgress from Kenji Yokoyama.
KYCircularProgress allows you to easily create circular progress indicators, or you can create progress indicators with a completely custom appearance using UIBezierPath. You can also specify whether to use a line fill or a gradient style of fill.
Here’s an image from the readme showing several progress indicators created with KYCircularProgress:
You can find KYCircularProgress on Github here.
A nice component for creating customizable progress indicators.