When is it appropriate to use Combine versus asynchronous/await?

When deciding between using Combine and async/await in Swift, it is important to consider the nature of the tasks you are handling and the concurrency model you prefer.

When to Use Combine

• Reactive Programming: Combine is well-suited for reactive programming paradigms where you need to handle streams of values over time, such as user interface events or network responses.
• Complex Data Pipelines: If your application requires complex data transformations, filtering, and combining multiple asynchronous data sources, Combine provides powerful operators to manage these tasks.
• Backwards Compatibility: Combine can be a good choice if you need to maintain compatibility with older codebases that already use completion handlers or other reactive frameworks.

When to Use async/await

• Simpler Syntax: The async/await syntax is more straightforward and easier to read, making it a good choice for simpler asynchronous tasks.
• Task Suspension: Async/await is ideal for tasks that involve waiting for a single asynchronous operation to complete, such as reading from disk or making a network request. The syntax clearly indicates where suspensions can occur, making the code easier to understand and maintain.
• Concurrency Safety: Swift's concurrency model, including async/await, provides strong guarantees about data race safety, especially when combined with actors and structured concurrency. This can simplify the management of concurrent tasks and reduce the risk of concurrency-related bugs.

Examples from WWDC Sessions

• Concurrency in Swift: The session "A Swift Tour: Explore Swift’s features and design" discusses how async/await is used to model task suspension in code, making it easier to handle asynchronous operations (Concurrency).
• Testing with async/await: The session "Go further with Swift Testing" explains how async/await can be used in test code to handle asynchronous conditions, allowing tests to run in parallel and making them more efficient (Asynchronous conditions).
• Migrating to Swift 6: The session "Migrate your app to Swift 6" highlights the benefits of adopting Swift's concurrency features, including async/await, to improve the clarity and safety of concurrency in your applications (Adopting concurrency features).

In summary, use Combine for complex reactive programming needs and async/await for simpler, more readable asynchronous code with strong concurrency safety guarantees.