iOS client for Grain
grain.social
ios
photography
atproto
fix: distinguish 404 thumbs from transient failures in favorites
The previous detection treated any LazyImage/Nuke failure as a
dangling CDN ref, so slow first loads marked healthy favorites as
Deleted. It also missed galleries whose thumb string was empty or
unparseable — LazyImage(url: nil) never loads and never fires a
completion, so the card sat blank.
- hydratedFavorites drops galleries with empty/invalid thumb URLs.
- Replace the Nuke probe with a URLSession HEAD that only marks a
uri broken on HTTP 404/410; transient errors stay retryable via
a new probedFavoriteUris set.
- Cover every loaded favorite instead of the top 9; rerun when
loadMore appends.
- Drop the .onCompletion handler and the DeletedGalleryCard path.
Broken uris are hidden at render time via a new visibleFavorites
computed property.
authored by
Hima Aramona
and committed by
Chad Miller
d762ecb3
24c3f4e4
+90
-58
+29
-9
Grain/ViewModels/ProfileDetailViewModel.swift
+29
-9
Grain/ViewModels/ProfileDetailViewModel.swift
···
23
23
var favoritesLoaded = false
24
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var isLoadingFavorites = false
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var favoritesError: Error?
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-
/// URIs of favorites whose thumbnail failed to load this session — usually
27
-
/// dangling refs to since-deleted blobs. Populated by the grid's LazyImage
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-
/// completion handler; applied on the next favorites load so the current
29
-
/// view doesn't reflow.
26
+
/// URIs whose thumb a HEAD probe has confirmed is gone (404/410) — usually
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+
/// dangling refs to since-deleted blobs. `visibleFavorites` filters these
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+
/// out at render time so they vanish without a "deleted" placeholder, and
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+
/// `hydratedFavorites` strips them on the next load so they stay gone.
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var brokenFavoriteUris: Set<String> = []
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+
/// URIs whose thumb has already been probed this session (either confirmed
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+
/// reachable or confirmed broken). Used to skip redundant HEAD requests
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+
/// when new favorite batches come in. Transient probe failures don't add
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+
/// here so they're retried next pass.
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+
var probedFavoriteUris: Set<String> = []
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+
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+
/// Favorites currently safe to render — drops anything a probe has
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+
/// confirmed broken. `favoriteGalleries` keeps the raw list so broken
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+
/// items can be retried if they come back; this computed view is what the
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+
/// grid iterates.
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var visibleFavorites: [GrainGallery] {
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favoriteGalleries.filter { !brokenFavoriteUris.contains($0.uri) }
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}
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private var galleryCursor: String?
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private(set) var hasMoreGalleries = true
···
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}
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/// Drops favorites that would render empty: galleries with no photos
161
-
/// (deleted or never-populated), and galleries whose thumbnail already
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-
/// failed to load this session (tracked in `brokenFavoriteUris`). Applied
163
-
/// on every load path so the dangling ones disappear on the next refresh.
174
+
/// (deleted or never-populated), galleries whose thumb URL is missing or
175
+
/// unparseable (LazyImage can't attempt a load so it'd sit blank forever),
176
+
/// and galleries whose thumbnail was already confirmed broken this session
177
+
/// (tracked in `brokenFavoriteUris`). Applied on every load path.
164
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private func hydratedFavorites(_ galleries: [GrainGallery]) -> [GrainGallery] {
165
-
galleries.filter {
166
-
!($0.items?.isEmpty ?? true) && !brokenFavoriteUris.contains($0.uri)
179
+
galleries.filter { gallery in
180
+
guard !(gallery.items?.isEmpty ?? true) else { return false }
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+
guard !brokenFavoriteUris.contains(gallery.uri) else { return false }
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+
guard let thumb = gallery.items?.first?.thumb,
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+
!thumb.isEmpty,
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+
URL(string: thumb) != nil
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else { return false }
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+
return true
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}
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}
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+61
-49
Grain/Views/Profile/ProfileView.swift
+61
-49
Grain/Views/Profile/ProfileView.swift
···
856
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.frame(maxWidth: .infinity)
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.padding(.top, 60)
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} else {
859
+
let visible = viewModel.visibleFavorites
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LazyVGrid(columns: [
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GridItem(.flexible(), spacing: 2),
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GridItem(.flexible(), spacing: 2),
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GridItem(.flexible(), spacing: 2),
863
864
], spacing: 2) {
864
-
ForEach(viewModel.favoriteGalleries) { gallery in
865
+
ForEach(visible) { gallery in
865
866
Button {
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selectedGallery = nil
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DispatchQueue.main.async {
···
871
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Color.clear
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.aspectRatio(3.0 / 4.0, contentMode: .fit)
873
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.overlay {
874
-
if viewModel.brokenFavoriteUris.contains(gallery.uri) {
875
-
DeletedGalleryCard()
876
-
} else if let photo = gallery.items?.first {
877
-
LazyImage(url: URL(string: photo.thumb)) { state in
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+
if let photo = gallery.items?.first, let url = URL(string: photo.thumb) {
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+
LazyImage(url: url) { state in
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if let image = state.image {
879
878
image
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.resizable()
···
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Rectangle().fill(.quaternary)
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}
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}
886
-
// Dangling blob refs (server returns an item
887
-
// but the CID 404s on the CDN) — mark the uri
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-
// so the next render swaps in the deleted
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-
// card, and the next favorites load filters
890
-
// it out entirely.
891
-
.onCompletion { result in
892
-
if case .failure = result {
893
-
viewModel.brokenFavoriteUris.insert(gallery.uri)
894
-
}
895
-
}
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} else {
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-
DeletedGalleryCard()
886
+
Rectangle().fill(.quaternary)
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}
899
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}
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.clipped()
···
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.buttonStyle(.plain)
913
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.matchedTransitionSource(id: gallery.uri, in: galleryZoomNS)
914
903
.onAppear {
915
-
if gallery.id == viewModel.favoriteGalleries.last?.id {
904
+
if gallery.id == visible.last?.id {
916
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Task { await viewModel.loadMoreFavorites(did: did, auth: auth.authContext()) }
917
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}
918
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}
919
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}
920
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}
921
-
// Eagerly probe the first few thumbs so broken ones above the
922
-
// LazyVGrid fold get marked before the user scrolls to them.
923
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// Keyed on the top-N uris so it reruns when the list head changes.
924
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.task(id: viewModel.favoriteGalleries.prefix(9).map(\.uri).joined(separator: "|")) {
925
-
await probeTopFavoriteThumbs(limit: 9)
910
+
// HEAD-probe every loaded favorite thumb so dangling CDN refs get
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+
// marked before render. Keyed on the full uri list so new batches
912
+
// from loadMore trigger a re-probe; probeFavoriteThumbs itself
913
+
// skips uris already checked this session.
914
+
.task(id: viewModel.favoriteGalleries.map(\.uri).joined(separator: "|")) {
915
+
await probeFavoriteThumbs()
926
916
}
927
917
}
928
918
}
929
919
930
-
private func probeTopFavoriteThumbs(limit: Int) async {
931
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let targets: [(uri: String, thumb: String?)] = viewModel.favoriteGalleries
932
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.prefix(limit)
933
-
.map { ($0.uri, $0.items?.first?.thumb) }
920
+
private func probeFavoriteThumbs() async {
921
+
let targets: [(uri: String, thumb: String)] = viewModel.favoriteGalleries.compactMap { gallery in
922
+
guard !viewModel.brokenFavoriteUris.contains(gallery.uri),
923
+
!viewModel.probedFavoriteUris.contains(gallery.uri),
924
+
let thumb = gallery.items?.first?.thumb,
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+
!thumb.isEmpty
926
+
else { return nil }
927
+
return (gallery.uri, thumb)
928
+
}
929
+
guard !targets.isEmpty else { return }
930
+
934
931
var broken: [String] = []
935
-
await withTaskGroup(of: (String, Bool).self) { group in
932
+
var probed: [String] = []
933
+
await withTaskGroup(of: FavoriteThumbProbe.self) { group in
936
934
for target in targets {
937
935
let uri = target.uri
938
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let thumb = target.thumb
939
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group.addTask {
940
-
guard let thumb, let url = URL(string: thumb) else {
941
-
return (uri, false)
938
+
guard let url = URL(string: thumb) else {
939
+
return FavoriteThumbProbe(uri: uri, result: .broken)
942
940
}
941
+
var req = URLRequest(url: url)
942
+
req.httpMethod = "HEAD"
943
+
req.timeoutInterval = 10
943
944
do {
944
-
_ = try await ImagePipeline.shared.image(for: url)
945
-
return (uri, true)
945
+
let (_, response) = try await URLSession.shared.data(for: req)
946
+
guard let http = response as? HTTPURLResponse else {
947
+
return FavoriteThumbProbe(uri: uri, result: .unknown)
948
+
}
949
+
if http.statusCode == 404 || http.statusCode == 410 {
950
+
return FavoriteThumbProbe(uri: uri, result: .broken)
951
+
}
952
+
return FavoriteThumbProbe(uri: uri, result: .ok)
946
953
} catch {
947
-
return (uri, false)
954
+
return FavoriteThumbProbe(uri: uri, result: .unknown)
948
955
}
949
956
}
950
957
}
951
-
for await (uri, ok) in group where !ok {
952
-
broken.append(uri)
958
+
for await probe in group {
959
+
switch probe.result {
960
+
case .broken:
961
+
broken.append(probe.uri)
962
+
probed.append(probe.uri)
963
+
case .ok:
964
+
probed.append(probe.uri)
965
+
case .unknown:
966
+
break
967
+
}
953
968
}
954
969
}
955
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for uri in broken {
956
971
viewModel.brokenFavoriteUris.insert(uri)
972
+
}
973
+
for uri in probed {
974
+
viewModel.probedFavoriteUris.insert(uri)
957
975
}
958
976
}
959
977
···
1125
1143
}
1126
1144
}
1127
1145
1128
-
private struct DeletedGalleryCard: View {
1129
-
var body: some View {
1130
-
Rectangle()
1131
-
.fill(.quaternary)
1132
-
.overlay {
1133
-
VStack(spacing: 6) {
1134
-
Image(systemName: "trash")
1135
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.font(.system(size: 18, weight: .regular))
1136
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.foregroundStyle(.secondary)
1137
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Text("Deleted")
1138
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.font(.caption2)
1139
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.foregroundStyle(.secondary)
1140
-
}
1141
-
}
1142
-
}
1146
+
private enum FavoriteThumbProbeResult {
1147
+
case ok
1148
+
case broken
1149
+
case unknown
1150
+
}
1151
+
1152
+
private struct FavoriteThumbProbe {
1153
+
let uri: String
1154
+
let result: FavoriteThumbProbeResult
1143
1155
}
1144
1156
1145
1157
#Preview {