CupertinoActivityIndicator constructor Null safety
Creates an iOS-style activity indicator that spins clockwise.
Implementation
const CupertinoActivityIndicator({
  super.key,
  this.color,
  this.animating = true,
  this.radius = _kDefaultIndicatorRadius,
})  : assert(animating != null),
      assert(radius != null),
      assert(radius > 0.0),
      progress = 1.0;