WWDC Notes

Swan's Quest, Chapter 2: A time for tones

Show Apple's description.
Swift Playgrounds presents "Swan’s Quest,” an interactive adventure in four chapters for all ages. In this chapter, our Hero needs your help decoding the Swan’s scroll. Call forth the best of your audio abilities on this one — you’re going to need them. Discover how to convert Swift Playgrounds into a tone generator, and you just might help our Hero find the missing message… and move onto the next part of their quest. Swan’s Quest was created for Swift Playgrounds on iPad and Mac, combining frameworks and resources which power the educational experiences in many of our playgrounds, including Sonic Workshop, Sensor Arcade, and Augmented Reality. To learn more about building your own playgrounds, be sure to watch "Create Swift Playgrounds content for iPad and Mac". And don’t forget to stop by the Developer Forums and share your solution for our side quest.

Swan's Quest is a series of challenges where each chapter has a specific programming challenge for you that will build on the prior chapters.

Download the .playgroundbook here.

Tones

For this first challenge, a SPCAudio PlaygroundModule has been built, this module is part of the Create Quest Playground Book.

In this challenge you will need to play a tone with the secret code given in the previous quest. All of this is done via a Timer and a SPCAudio's' Tone.

Solution

Advice from the Lizard

let toneOutput = ToneOutput()

func performance(owner: Assessable) {
    
    let tones = [
        Tone(pitch: 440.00, volume: 0.3),
        Tone(pitch: 493.88, volume: 0.3),
        Tone(pitch: 523.25, volume: 0.3) 
    ]
    
    var toneIndex = 0
    Timer.scheduledTimer(withTimeInterval: 0.4, repeats: true) { timer in
        guard toneIndex < tones.count else {
            toneOutput.stopTones()
            timer.invalidate()
            owner.endPerformance()
            return
        }
        
        toneOutput.play(tone: tones[toneIndex])
        toneIndex += 1
    }
    // Let it be known your performance has ended.
    owner.endPerformance()
}

Performance at Swan Hall

func performance(owner: Assessable) {
    let toneOutput = ToneOutput()
    
    // TODO: Code your performance here.
    let tones = [261.63, 293.66, 329.63, 349.23, 392.00, 440.00, 493.88, 523.25].map({ Tone(pitch: $0, volume: 0.3)})
    
    var toneIndex = 0
    Timer.scheduledTimer(withTimeInterval: 0.4, repeats: true) { timer in
        guard toneIndex < tones.count else {
            toneOutput.stopTones()
            timer.invalidate()
            owner.endPerformance()
            return
        }
        
        toneOutput.play(tone: tones[toneIndex])
        toneIndex += 1
    }
    
    // Let it be known your performance has ended.
    owner.endPerformance()
}

Missing anything? Corrections? Contributions are welcome 😃

Related

Written by

zntfdr

Federico Zanetello

Federico Zanetello is an iOS Engineer with strong passion for Swift, minimalism, and design. When he’s not busy automating things, he can be found writing at fivestars.blog and/or playing with the latest shiny toys.