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fix: missing poster image bailing on thumbnails #3754

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Merged
isekovanic merged 3 commits into from
Aug 5, 2026
+17 −4
Merged

fix: missing poster image bailing on thumbnails #3754

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1efb351
fix: thumbnail generation failures on missing poster images
isekovanic Aug 5, 2026
40f3573
fix: settle on lower size
isekovanic Aug 5, 2026
92e3f63
chore: add comments
isekovanic Aug 5, 2026
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21 changes: 17 additions & 4 deletions package/shared-native/ios/StreamVideoThumbnailGenerator.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,11 @@ public final class StreamVideoThumbnailResult: NSObject {
@objcMembers
public final class StreamVideoThumbnailGenerator: NSObject {
private static let compressionQuality: CGFloat = 0.8
private static let maxDimension: CGFloat = 512
// We intentionally use a lower maxDimension for iOS, as we are trying to mimic
// what a .fastFormat delivery type of the image would do. Although theoretically
// smaller (around 120px) after some benchmarking we figured that 256 was perfectly
// fine and adds just a tiny bit of overhead for a visible quality increase.
private static let maxDimension: CGFloat = 256
private static let cacheVersion = "v1"
private static let cacheDirectoryName = "@stream-io-stream-video-thumbnails"
private static let maxConcurrentGenerations = 5
Expand Down Expand Up @@ -209,7 +213,16 @@ public final class StreamVideoThumbnailGenerator: NSObject {
// serves a locally cached thumbnail even for iCloud only assets, so this
// avoids downloading the entire video the way requestAVAsset(forVideo:) would.
let options = PHImageRequestOptions()
options.deliveryMode = .fastFormat
// `.highQualityFormat` instead of `.fastFormat` here, as the latter only serves
// an already cached poster derivative and will NOT generate one on demand, so
// it fails (PHPhotosError 3303) for assets that have no cached thumbnail yet,
// i.e videos added to a Simulator via `simctl addmedia`, which never get
// their derivatives generated. `.highQualityFormat` still delivers a single
// final image (matching the "accept the first delivered image" logic below)
// and only fetches the poster frame, not the whole video. If a poster frame does
// not exist, it will generate one on the fly (only the first time, all subsequent
// request will return the cached one).
options.deliveryMode = .highQualityFormat
options.resizeMode = .fast
options.isNetworkAccessAllowed = true
options.isSynchronous = false
Expand Down Expand Up @@ -262,8 +275,8 @@ public final class StreamVideoThumbnailGenerator: NSObject {
contentMode: .aspectFit,
options: options
) { image, info in
// Accept the first delivered image (.fastFormat sends exactly one,
// thumbnail quality, possibly flagged degraded and that's what we want).
// Accept the first delivered image (.highQualityFormat sends exactly
// one and we still guard against any extra deliveries).
state.lock.lock()
if state.didResume {
state.lock.unlock()
Expand Down