Swift Library Design

Patterns and best practices for designing high-quality Swift libraries and frameworks.

Core Principles

1. Protocol-Oriented Design

Design around protocols with associated types for flexibility and testability. Use generics for type safety with runtime polymorphism.

2. Compile-Time Safety

Leverage Swift's type system to catch errors at compile time. Use noncopyable types, generics, and protocol constraints to make invalid states unrepresentable.

3. Performance by Default

Design APIs that are efficient by default. Use @inlinable for hot paths, avoid unnecessary allocations, and provide zero-copy options.

4. Progressive Disclosure

Simple things should be simple, complex things should be possible. Provide sensible defaults while allowing customization.

Key Patterns