The animation that I developed is a simple circular CAShapeLayer with a lineDashPattern modifying its line. In addition, a CAShapeLayer with doughnut form is attached to the mask of that circle (above image). The circle is the firework itself. Instead, the doughnut is only used as a mask to vanish the firework with an animation (explained in the next section).

Line Dash Patterned Circle

let firework: CAShapeLayer = CAShapeLayer()
firework.lineDashPattern = [sparkThickness, sparkSeparation] as [NSNumber]

let circlePath = UIBezierPath(arcCenter: CGPoint(x: radius, y: radius),
radius: radius,
startAngle: CGFloat(0.0),
endAngle: CGFloat(Double.pi*2),
clockwise: false)

firework.path = circlePath.cgPath
firework.mask = mask(radius: radius)

2017.08

Swift Fireworks