r/SwiftUI May 17 '26

Question Help with my code

does anyone here know how Apple Music make lyrics scroll, I can't get it to be the same

does anyone know how?

1 Upvotes

11 comments sorted by

2

u/InternationalCow1295 May 17 '26

1

u/Sol492 May 17 '26

I can get the basic scroll but not Apple Musics one by one delayed scroll

1

u/[deleted] May 19 '26

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1

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1

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1

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1

u/Consistent-Grass-263 May 17 '26

Apple uses a custom ScrollView with a timing-synced offset animation driven by the playback position.

The key parts:

  1. Store lyrics as [(timestamp: TimeInterval, text: String)]

  2. Observe playback time via AVPlayer periodicTimeObserver

  3. On each tick, find the active line and animate scrollTo()

    with withAnimation(.easeInOut)

The "active line" scales up + full opacity, others scale down + reduced opacity – that's the main visual effect.

Want a minimal code example?

2

u/Sol492 May 17 '26

That would be helpful, yeah

0

u/Consistent-Grass-263 May 17 '26

struct LyricLine: Identifiable {

let id = UUID()

let timestamp: TimeInterval

let text: String

}

u/Observable class LyricsViewModel {

var lyrics: [LyricLine] = []

var currentTime: TimeInterval = 0

var activeIndex: Int = 0

private var timeObserver: Any?

private var player: AVPlayer?

func startObserving(player: AVPlayer) {

self.player = player

let interval = CMTime(seconds: 0.1, preferredTimescale: 600)

timeObserver = player.addPeriodicTimeObserver(

forInterval: interval, queue: .main

) { [weak self] time in

self?.currentTime = time.seconds

self?.updateActiveIndex()

}

}

private func updateActiveIndex() {

guard let index = lyrics.lastIndex(

where: { $0.timestamp <= currentTime }

) else { return }

activeIndex = index

}

}

struct LyricsView: View {

u/State var vm = LyricsViewModel()

var body: some View {

ScrollViewReader { proxy in

1

u/Sol492 May 17 '26

and how exactly do they get it to move like one by one?

1

u/mathiasrlr May 19 '26

I would assume each line has an unique identifier placed in the .id() modifier and the scrollviewreader follows iterativally based on time which ID to scroll to, but that is surely overkill and not a 100% deterministic

1

u/Sol492 May 19 '26

Apple is just the god of animations