SwiftUI Scroll Offset

Track ScrollView offset in SwiftUI with a simple modifier. Perfect for collapsing headers, parallax effects, and scroll-driven animations.

Installation

https://github.com/tjdrhs90/swiftui-scroll-offset.git

Usage

Basic

import ScrollOffset

struct ContentView: View {
    @State private var offset: CGPoint = .zero

    var body: some View {
        VStack {
            // Use as a wrapper
            OffsetTrackingScrollView { offset in
                self.offset = offset
            } content: {
                ForEach(0..<50) { i in
                    Text("Row \(i)")
                        .padding()
                }
            }
        }
    }
}

Collapsing Header

struct HeaderView: View {
    @State private var offset: CGPoint = .zero

    var body: some View {
        ZStack(alignment: .top) {
            OffsetTrackingScrollView { offset in
                self.offset = offset
            } content: {
                LazyVStack {
                    ForEach(0..<100) { i in
                        Text("Item \(i)")
                            .frame(maxWidth: .infinity)
                            .padding()
                    }
                }
            }

            // Header that collapses on scroll
            Text("Header")
                .frame(maxWidth: .infinity)
                .frame(height: max(60, 120 - offset.y))
                .background(.ultraThinMaterial)
        }
    }
}

View Modifier Style

VStack {
    ForEach(0..<50) { i in
        Text("Row \(i)").padding()
    }
}
.trackScrollOffset { offset in
    print("y: \(offset.y)")
}

How It Works

Uses GeometryReader + PreferenceKey inside a coordinateSpace to read the scroll position without interfering with the layout. Zero performance overhead.

Requirements

• iOS 15+
• Swift 5.9+
• Xcode 15+

License

MIT License. See LICENSE for details.