Sorry for the delay on getting a response to this. We've had some problems with not getting notifications when forum posts are made.
There is a SpriteKit example of our particle system on github at https://github.com/71squared/ParticleEmitterDemo-SK
This is still Objective-C but will work alongside Swift until we get around to doing a Swift version. We have not had many requests for a Swift version which is why its not got to the top of the list yet.
If you can email [email protected] with details of your original purchase I'll get a discount code over to you for Particle Designer 2.0.