NEW: My free 100 Days of SwiftUI challenge starts tomorrow! >>

How to emit particles using CAEmitterLayer

Swift version: 5.0

Paul Hudson    @twostraws   

Believe it or not, iOS has a built-in particle system that works great in all UIKit apps and is immensely customizable. To get started you need to create a CAEmitterLayer object and tell it how to create particles: where it should create them, how big the emitter should be, and what types of particles should exist.

The "type of particles" part is handled by CAEmitterCell, which covers details like how fast to create, how long they should live, whether they should spin and/or fade out, what texture to use, and more. You can add as many CAEmitterCells to a CAEmitterLayer as you need.

Here's some example code to get you started. This creates particles of three different colors, all falling and spinning down from the top of the screen. The image "particle_confetti" is just a small white triangle that I drew by hand – you should replace that with something more interesting.

func createParticles() {
    let particleEmitter = CAEmitterLayer()

    particleEmitter.emitterPosition = CGPoint(x: view.center.x, y: -96)
    particleEmitter.emitterShape = .line
    particleEmitter.emitterSize = CGSize(width: view.frame.size.width, height: 1)

    let red = makeEmitterCell(color: UIColor.red)
    let green = makeEmitterCell(color: UIColor.green)
    let blue = makeEmitterCell(color: UIColor.blue)

    particleEmitter.emitterCells = [red, green, blue]

    view.layer.addSublayer(particleEmitter)
}

func makeEmitterCell(color: UIColor) -> CAEmitterCell {
    let cell = CAEmitterCell()
    cell.birthRate = 3
    cell.lifetime = 7.0
    cell.lifetimeRange = 0
    cell.color = color.cgColor
    cell.velocity = 200
    cell.velocityRange = 50
    cell.emissionLongitude = CGFloat.pi
    cell.emissionRange = CGFloat.pi / 4
    cell.spin = 2
    cell.spinRange = 3
    cell.scaleRange = 0.5
    cell.scaleSpeed = -0.05

    cell.contents = UIImage(named: "particle_confetti")?.cgImage
    return cell
}

LEARN SWIFTUI FOR FREE I wrote a massive, free SwiftUI tutorial collection, and also have a growing list of free SwiftUI tutorials on YouTube – get started today!

Available from iOS 5.0 – see Hacking with Swift tutorial 37

Similar solutions…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

MASTER SWIFT NOW
Buy Testing Swift Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.5/5