CachedAsyncImage

🔍 Overview

CachedAsyncImage is a SwiftUI view that loads and displays an image from a URL, using both in-memory and disk-based caching. It's optimized for performance and memory efficiency, designed to prevent unnecessary image reloads across sessions.

It is designed to work seamlessly with CustomImage, providing a robust image pipeline.

🧱 Structure

🔄 ImageCacheManager

• Singleton class managing image caching
• Two-tier caching: memory (via NSCache) and disk (via FileManager)
• Uses a custom CacheImageWrapper to track memory cost and log evictions

🧠 MemoryUsageTracker

• Swift actor responsible for tracking memory usage asynchronously
• Ensures accurate cost accounting when images are evicted

📥 ImageLoader

• Deduplicates fetches for the same URL
• Publishes the image state and failure flags
• Supports loading images via URLSession and promotes disk images into memory cache

🖼️ View: CachedAsyncImage

struct CachedAsyncImage<Content: View, Placeholder: View>: View {
    init(
        url: URL,
        @ViewBuilder content: @escaping (Image) -> Content,
        @ViewBuilder placeholder: @escaping () -> Placeholder
    )
}

🔄 Image Fetch Flow

1. Try to fetch from in-memory cache
2. Fallback to disk cache if not found
3. If not on disk, download via URLSession
4. On success, store in both memory and disk
5. If it fails, show placeholder

📦 Features

• 🧠 Memory usage tracking with total size limits
• 💾 Disk cache for persistence across launches
• 🔄 Automatic promotion of disk image to memory cache
• 🧪 Remote image validation using NSDataDetector

💡 Usage Example

CachedAsyncImage(url: URL(string: "https://example.com/image.png")!) { image in
    image
        .resizable()
} placeholder: {
    ProgressView()
}

🌉 Integration with CustomImage

CachedAsyncImage is the backend renderer for remote images used in the CustomImage component:

CustomImage.remote(
    url: ...,
    imageColor: ...,
    placeholder: ...,
    placeholderColor: ...
).view()

👉 See the CustomImage Documentation for recommended usage and API details.

🧭 Navigation

See also: CustomImage