How can SwiftUI animations be isolated to child views? - animation

Question

I'm trying to animate a transformation within a cell of a grid view, but I don't want this animation to affect the layout of the cells as they are repositioned by data changes. I feel like this should be simple to do, but it doesn't work no matter what I try.
Perhaps someone can demonstrate SwiftUI where cells in a grid view can reorder themselves without a spring animation while the cells use a spring animation to resize locally? That would be greatly appreciated!
var body: some View {
LazyVGrid(columns) {
ForEach(dataSource.dataList) { // This is an array of structs
CellView(data: $0)
}
}
.animation(.default)
}
struct CellView: View {
let data: CellData
#State var contentScale: CGFloat = 1
init(data: CellData) {
self.data = data
let anim = Animation.interpolatingSpring(stiffness: 50, damping: 5)
withAnimation(anim) {
self.contentScale = calcScaleFrom(data: data)
}
}
var body: some View {
// Configure cell with data
// and animate scale based on data properties
}
}

Answer 1

Ok, I didn't find the answer to my exact question... but I did find a workaround. My precise aim was making my cells update their content with a spring animation, but making the grid reorder the cell with the default animation. To do this I simply added a withAnimation block in my grid's data model code which selects the style of animation based on whether the data list changed order!
#Published var currentList: [CellData]
func updateData() {
let newList = ...
let anim: Animation
if newList.map({$0.id}).elementsEqual(currentList.map({$0.id})) {
// Data may have changed but does not require any cell reordering
anim = Animation.interpolatingSpring(stiffness: 80, damping: 5)
} else {
// Cells will change order!
anim = .default
}
withAnimation(anim) {
currentList = newList
}
}