SwiftUI - SnapDraggingModifier

This is a small SwiftUI package that allows for the creation of a draggable view and tracks the velocity of the dragging action, which can be used to create fluid animations when the drag is released. This component is a big help in creating interactive user interfaces and enhancing their fluidity.

About Fluid interfaces : https://developer.apple.com/videos/play/wwdc2018/803/

Examples

Throwing a ball

Circle()
  .fill(Color.blue)
  .frame(width: 100, height: 100)
  .modifier(SnapDraggingModifier())

---

Fixed draggable direction and rubber banding effect

RoundedRectangle(cornerRadius: 16, style: .continuous)
  .fill(Color.blue)
  .frame(width: 120, height: 50)
  .modifier(
    SnapDraggingModifier(
      axis: [.vertical],
      verticalBoundary: .init(min: -10, max: 10, bandLength: 50)
    )
  )

---

Thowing to the point

“The modifier asks for the destination point when the gesture ends, and the view will smoothly move to the specified point with velocity-based animation.”

RoundedRectangle(cornerRadius: 16, style: .continuous)
  .fill(Color.blue)
  .frame(width: nil, height: 50)
  .modifier(
    SnapDraggingModifier(
      axis: .horizontal,
      horizontalBoundary: .init(min: 0, max: .infinity, bandLength: 50),
      handler: .init(onEndDragging: { velocity, offset, contentSize in

        print(velocity, offset, contentSize)

        if velocity.dx > 50 || offset.width > (contentSize.width / 2) {
          print("remove")
          return .init(width: contentSize.width, height: 0)
        } else {
          print("stay")
          return .zero
        }
      })
    )
  )