A Swift library for fast diffing between collections, enabling efficient UI updates in iOS/macOS apps.
Differ is a Swift library that generates differences and patches between two collections, such as arrays or strings. It solves the problem of efficiently updating user interfaces by calculating only the insertions, deletions, and moves needed to transform one collection into another, enabling smooth animations in iOS and macOS apps.
iOS and macOS developers who need to animate table views, collection views, or other UI components based on changes in their data models.
Developers choose Differ for its fast diffing algorithm, which is significantly more performant than naive approaches, and its built-in utilities for animating UIKit and AppKit components without manual index calculations.
Swift library to generate differences and patches between collections.
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Uses an O((N+M)*D) algorithm that significantly outperforms naive O(n*m) approaches, with benchmarks showing orders of magnitude faster calculation times for common use cases, as detailed in the performance notes.
Provides convenient extensions for UITableView, UICollectionView, and their AppKit counterparts, allowing developers to animate insertions, deletions, and moves with minimal code, as demonstrated in the examples.
Supports arbitrary ordering of patches via custom sort functions, enabling advanced control over how differences are applied, which is useful for complex state transitions.
Can calculate differences between collections containing other collections using NestedDiff, making it suitable for hierarchical data structures without manual flattening.
The algorithm works best with small differences between collections; for large diffs, performance can suffer, and the README admits that alternatives like Hunt & Szymanski's algorithm might be more suitable, limiting its use in data-heavy applications.
While utilities simplify UI updates, they tightly couple the library to Apple's frameworks, making it less useful for Swift projects outside iOS/macOS or for non-UI diffing needs, reducing versatility.
The updateData closure requirement for UICollectionView animations, highlighted in the README, adds complexity and risk of crashes if not handled correctly, demanding careful attention to detail during implementation.