I'm playing with SwiftUI and I'm currently struggling with images. Basically, I want to display an list of images with an infinite scroll but I want to keep the memory usage reasonable.
I have the following (truncated) code:
struct HomeView: View {
@State private var wallpapers: Loadable<[Wallpaper]> = .notRequested
@State private var currentPage = 1
@Environment(\.container) private var container
var body: some View {
content
.onAppear { loadWallpapers() }
}
private var content: some View {
VStack {
wallpapersList(data: wallpapers.value ?? [])
// ...
}
}
private func wallpapersList(data: [Wallpaper]) -> some View {
ScrollView {
LazyVStack(spacing: 5) {
ForEach(data) { w in
networkImage(url: w.thumbs.original)
.onAppear { loadNextPage(current: w.id) }
}
}
}
}
private func networkImage(url: String) -> some View {
// I use https://github.com/onevcat/Kingfisher to handle image loading
KFImage(URL(string: url))
// ...
}
private func loadWallpapers() {
container.interactors.wallpapers.load(data: $wallpapers, page: currentPage)
}
private func loadNextPage(current: String) {
// ...
}
}
struct WallpapersInteractor: PWallpapersInteractor {
let state: Store<AppState>
let agent: PWallpapersAgent
func load(data: LoadableSubject<[Wallpaper]>, page: Int) {
let store = CancelBag()
data.wrappedValue.setLoading(store: store)
Just.withErrorType((), Error.self)
.flatMap { _ in
agent.loadWallpapers(page: page) // network call here
}
.map { response in
response.data
}
.sink { subCompletion in
if case let .failure(error) = subCompletion {
data.wrappedValue.setFailed(error: error)
}
} receiveValue: {
if var currentWallpapers = data.wrappedValue.value {
currentWallpapers.append(contentsOf: $0) // /!\
data.wrappedValue.setLoaded(value: currentWallpapers)
} else {
data.wrappedValue.setLoaded(value: $0)
}
}
.store(in: store)
}
}
Because I append the new data to my Binding every time I request a new batch of images, the memory consumption quickly becomes stupidly high.
I tried to remove data from the array using .removeFirst(pageSize) once I get to the third page so that my array contains at most 2 * pageSize elements (pageSize being 64 in this case). But doing so makes my list all jumpy because the content goes up, which creates more problems than it solves.
I tried searching for a solution but I surprisingly didn't find anything on this particular topic, am I missing something obvious ?