Demo: improved RemoteImage and ImageCache modules

Author: crontab

AsyncMuxDemo/Sources/RemoteImage/ImageCache.swift

@@ -12,41 +12,31 @@ import AsyncMux
 private let CacheCapacity = 20
 
 
+@MainActor
 final class ImageCache {
 
     static func request(_ url: URL) async throws -> UIImage {
         if let image = loadFromMemory(url) {
             return image
         }
         let image = try await requestRemote(url)
-        storeToMemory(url: url, image: image)
+        memCache.set(image, forKey: url)
         return image
     }
 
 
     static func loadFromMemory(_ url: URL) -> UIImage? {
-        semaphore.wait()
-        defer { semaphore.signal() }
-        return memCache.touch(key: url)
+        memCache.touch(key: url)
     }
 
 
     static func clear() {
-        semaphore.wait()
-        defer { semaphore.signal() }
         memCache.removeAll()
     }
 
-
+    
     // MARK: - Private part
 
-    private static func storeToMemory(url: URL, image: UIImage) {
-        semaphore.wait()
-        defer { semaphore.signal() }
-        memCache.set(image, forKey: url)
-    }
-
-
     @AsyncMediaActor
     private static func requestRemote(_ url: URL) async throws -> UIImage {
         let localURL = try await AsyncMedia.request(url: url)
@@ -58,8 +48,7 @@ final class ImageCache {
     }
 
 
-    nonisolated(unsafe)
     private static var memCache = LRUCache<URL, UIImage>(capacity: CacheCapacity)
 
-    private static let semaphore = DispatchSemaphore(value: 1)
+    private init() { }
 }

AsyncMuxDemo/Sources/RemoteImage/RemoteImage.swift

@@ -28,11 +28,17 @@ struct RemoteImage<P: View, I: View>: View {
             }
         }
         .onChange(of: url, initial: true) { oldValue, newValue in
+            // Try sync load first
+            if let newValue, let image = ImageCache.loadFromMemory(newValue) {
+                uiImage = image
+                return
+            }
             uiImage = nil
             error = nil
             if let newValue {
                 Task {
                     do {
+                        // Now try loading from disk or downloading remote
                         self.uiImage = try await ImageCache.request(newValue)
                     }
                     catch {