How to use Fast Image Cache with Swift in iOS?

Since Fast Image Cache is written in Objective-C, integrate it via bridging header and implement FICEntity in Swift classes. However, be prepared for potential issues with Swift interoperability and lack of updates for newer iOS versions.

Fast Image Cache vs SDWebImage: which is better for iOS?

Fast Image Cache excels in raw scrolling performance for small, pre-processed images using memory mapping, while SDWebImage offers more features like network loading, WebP support, and active maintenance. Choose based on performance needs versus convenience and modern support.

How to handle network image loading with Fast Image Cache?

Fast Image Cache doesn't handle networking; you must implement the delegate method to fetch images from URLs. Use URLSession or third-party libraries to download images, then pass them to the cache via the completion block.

What are the disk space implications of using Fast Image Cache?

It uses uncompressed image data, so cache files are larger—e.g., a 50x50 ARGB image takes about 10KB uncompressed vs. 2KB compressed. This can quickly add up, impacting device storage and cache management.

Can Fast Image Cache be used for background image processing?

Yes, it processes images in its own serial queue, but you must configure data protection modes correctly if accessing cache files when the device is locked, as iOS may encrypt the disk and block access.

How to cancel image requests in Fast Image Cache?

Call cancelImageRetrievalForEntity:withFormatName: on the cache, and ensure your delegate also cancels any ongoing network requests. This prevents wasted resources when images are no longer needed, such as during fast scrolling.

Open-Awesome

FastImageCache

MITObjective-C1.5.1

An iOS library for fast, smooth image display in scrollable views using memory-mapped image tables.

GitHub

8.1k stars921 forks0 contributors

What is FastImageCache?

Fast Image Cache is an iOS library that enables fast, smooth display of images in scrollable views like tables and collections. It solves the performance problem of traditional image loading, which can cause dropped frames and janky scrolling, by using memory-mapped image tables and pre-decoded bitmap storage.

Target Audience

iOS developers building graphics-rich applications, such as social networks or photo galleries, where smooth scrolling with many images is critical for user experience.

Value Proposition

Developers choose Fast Image Cache because it provides near-instant image retrieval, maintains 60FPS scrolling, and reduces memory pressure compared to standard UIImage loading, all through a model-based API that integrates cleanly with existing data structures.

Overview

iOS library for quickly displaying images while scrolling

Use Cases

Best For

Social networking apps displaying user photos in feeds
Photo gallery applications with smooth scrolling thumbnails
iOS apps requiring high-performance image loading in UITableView or UICollectionView
Applications that need to display many small images without dropping frames
Projects where traditional UIImage loading causes scrolling lag
Apps that cache processed images (e.g., rounded thumbnails) for reuse

Not Ideal For

Applications dealing with large, high-resolution images where disk space is limited
Swift-only projects looking for a modern, actively maintained caching library
Teams needing a drop-in solution without implementing custom entity protocols
Projects where cache persistence across app updates is critical, as image tables are stored in caches directory and can be purged by iOS

Pros & Cons

Pros

Memory-Mapped Performance

Uses mmap to map image tables directly into memory, eliminating buffer copies and reducing real memory usage, as explained in the README's mapped memory section.

Avoids Decompression Overhead

Stores images as uncompressed bitmaps, so expensive JPEG decompression happens only once per image, ensuring fast retrieval for repeated displays.

Core Animation Optimization

Ensures proper byte alignment for images, preventing Core Animation from creating unnecessary copies and maintaining 60FPS scrolling, crucial for smooth UI.

Automatic Cache Management

Manages cache expiry based on recency and replaces least-recently-used images when full, simplifying cache maintenance.

Cons

High Disk Space Usage

Stores images uncompressed, leading to significantly larger cache files compared to compressed formats, which can be a concern for devices with limited storage.

Complex Integration

Requires implementing the FICEntity protocol for each model object and handling image fetching via delegate, adding setup overhead compared to simpler libraries.

Outdated and Unmaintained

Last updated in 2014 with iOS 6+ support, making it potentially incompatible with modern iOS features and Swift projects without additional work.

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