ParallaxScrollView

An extended SwiftUI.ScrollView with support for a sticky header that collapses to a compact size during scroll.

Instalation

ParallaxScrollView is available via Swift Package Manager.

dependencies: [
  .package(url: "https://github.com/mtzaquia/parallax-scrollview.git", from: "1.0.2"),
],

Usage

Use ParallaxScrollView like a regular, vertical scroll view. The main difference is the header parameter.

@State var isCollapsed = false

/* ... */

ParallaxScrollView {
  ParallaxHeader(defaultHeight: 300) { // an arbitrary, expanded height, or `nil`.
    // an example of a header with a gradient for sufficient contrast with the background image.
    myHeader()
      .background {
        LinearGradient(
          colors: [
            .clear,
            .black.opacity(0.4),
            .black
          ],
          startPoint: .top,
          endPoint: .bottom
        )
        .ignoresSafeArea() // safe area applies when collapsed.
      }
  } background: {
    // an example of an image that blurs when collapsed.
    myImage()
      .resizable()
      .aspectRatio(contentMode: .fill)
      .animation(nil, value: isCollapsed) // avoids unwanted frame animation during scroll.
      .blur(radius: isCollapsed ? 3 : 0)
      .animation(.snappy, value: isCollapsed)
  }
} content: {
  myScrollableContent()
} onCollapsedChanged: { // optional callback to observe collapse state changes to tweak header/background design accordingly.
  isCollapsed = $0 
}

Acknowledgements

• Thanks to @chrisjrex for rubber ducking on a nearly daily basis.
• Thanks to @danielsaidi's ScrollKit for inspiration on offset tracking using PreferenceKey.

License

Copyright (c) 2024 @mtzaquia

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.