day-071

Day 71: Project 20: Fireworks Night, Part Two

This day covers the second and final part of Project 20: Fireworks Night in Hacking with Swift. You can follow along directly here.

📒 Field Notes

I previously created projects alongside Hacking with Swift in a separate repository. For 100 Days of Swift, however, I've been extending things further and adding my revised projects to this repo under each "Part One" folder.

With that in mind, Day 71 focuses on using SKEmitterNode to trigger explosions. Then it finishes by extending the project with a set of challenges.

Making Things Go Bang: SKEmitterNode

Because we're using the device's motion to explode fireworks, it's important for our game scene's view controller to be able to communicate with the game scene itself. By overriding its motionBegan hook we can do exactly that:

override func motionBegan(_ motion: UIEvent.EventSubtype, with event: UIEvent?) {
    guard
        let spriteKitView = self.view as? SKView,
        let gameScene = spriteKitView.scene as? MainGameScene
    else {
        preconditionFailure("Failed to find SKView and MainGameScene")
    }

    gameScene.explodeSelectedFireworks()
}

explodeSelectedFireworks, then, lives in our SKScene class, and it handles updating the player's current score, finding each complete group of firework nodes with a rocket child node that was selected, and then running an explosion effect at its current position:

func explodeSelectedFireworks() {
    currentScore += pointsToAward
    selectedRockets.removeAll(keepingCapacity: true)

    for (index, firework) in fireworks.enumerated().reversed() {
        if firework.children.contains(where: { $0.name == NodeName.selectedFireworkRocket }) {
            fireworks.remove(at: index)
            explode(firework: firework)
        }
    }
}

func explode(firework: SKNode) {
    let emitter = SKEmitterNode(fileNamed: "explode")!

    emitter.position = firework.position
    addChild(emitter)
    firework.removeFromParent()
}

If I were doing this project again, I'd probably create models for each firework that contained logic for navigating its node structure and searching for selected rockets. That would prevent keeping loose arrays in the main game scene class and iterating through them in each of these functions. In any case, though, things are going 💥.

🥅 Challenges

Challenge 1

For an easy challenge try adding a score label that updates as the player’s score changes.

• 🔗 Already Covered 🙂

Challenge 2

Make the game end after a certain number of launches. You will need to use the invalidate() method of Timer to stop it from repeating.

• 🔗 [Commit](General feedback and discussion for Day 70.)

Challenge 3

Use the waitForDuration and removeFromParent actions in a sequence to make sure explosion particle emitters are removed from the game scene when they are finished.

• 🔗 Commit