NEW: Subscribe to Hacking with Swift+ and accelerate your learning! >>

How to create 3D effects like Cover Flow using ScrollView and GeometryReader

Paul Hudson    @twostraws   

Updated for Xcode 12.0

If we combine GeometryReader with any view that can change position – such as something that has a drag gestures or is inside a List – we can create 3D effects very easily. GeometryReader allows us to read the coordinates for a view, and feed those values directly into a rotation3DEffect() modifier.

For example, we could create a Cover Flow-style scrolling effect by stacking up many text views horizontally in a scroll view, then applying rotation3DEffect() so that as they move in the scroll view they gently spin, like this:

struct ContentView: View {
    var body: some View {
        ScrollView(.horizontal, showsIndicators: false) {
            HStack(spacing: 0) {
                ForEach(1..<10) { num in
                    VStack {
                        GeometryReader { geo in
                            Text("Number \(num)")
                                .font(.largeTitle)
                            .padding()
                            .background(Color.red)
                            .rotation3DEffect(.degrees(-Double(geo.frame(in: .global).minX) / 8), axis: (x: 0, y: 1, z: 0))
                        }
                    }
                    .frame(width: 180)
                }
            }
            .padding()
        }
    }
}

We could something similar with a DragGesture() – this code creates a card-like rectangle that can be dragged around in both X and Y axes, and uses two rotation3DEffect() modifiers to apply values from GeometryReader:

struct ContentView: View {
    @State var dragAmount = CGSize.zero

    var body: some View {
        VStack {
            GeometryReader { geo in
                Rectangle()
                    .fill(LinearGradient(gradient: Gradient(colors: [.yellow, .red]), startPoint: .topLeading, endPoint: .bottomTrailing))
                    .frame(width: 300, height: 200)
                    .clipShape(RoundedRectangle(cornerRadius: 20))
                    .rotation3DEffect(.degrees(-Double(self.dragAmount.width) / 20), axis: (x: 0, y: 1, z: 0))
                    .rotation3DEffect(.degrees(Double(self.dragAmount.height / 20)), axis: (x: 1, y: 0, z: 0))
                    .offset(self.dragAmount)
                    .gesture(
                        DragGesture()
                            .onChanged { self.dragAmount = $0.translation }
                            .onEnded { _ in
                                withAnimation(.spring()) {
                                    self.dragAmount = .zero
                                }
                            }
                    )
            }
        }
    }
}

As you drag the card around you’ll see it rotates to give a perspective effect.

Hacking with Swift is sponsored by Instabug

SPONSORED Are you tired of wasting time debugging your Swift app? Instabug’s SDK is here to help you minimize debugging time by providing you with complete device details, network logs, and reproduction steps with every bug report. All data is attached automatically, and it only takes a line of code to setup. Start your free trial now and get 3 months off exclusively for the Hacking with Swift Community.

Start your free trial!

Sponsor Hacking with Swift and reach the world's largest Swift community!

Similar solutions…

BUY OUR BOOKS
Buy Pro Swift Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift (Vapor Edition) Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 3.7/5

Link copied to your pasteboard.