Particle emitters for apps with CAEmitterLayer on iOS

Particle emitters are encountered the most often in games. Apple's SpriteKit framework contains SKEmitterNode for this exact purpose. Moreover, Xcode even has a live editor for configuring SKEmitterNode. As SKEmitterNode can only be added to SKScene, it is not a good fit for apps. But no worries, apps can take advantage of CAEmitterLayer which is …