Nakiboddin Saiyad

Posted on Jul 16

Async/Await in Swift: Best Practices and Pitfalls to Avoid

#swift #ios #iphone #gftwhackathon

With the release of Swift 5.5, Apple introduced native support for async/await, transforming how asynchronous code is written in iOS and macOS applications. This long-awaited feature simplifies concurrency, making your code easier to read, debug, and maintain. However, like all tools, it comes with both advantages and traps.

If you're planning to build or scale your iOS application, it’s important to understand how to use async/await effectively or partner with professionals who do. Many businesses now hire Swift developers with hands-on experience in Swift concurrency to ensure efficient, scalable, and bug-free applications.

What is Async/Await in Swift?

Traditionally, iOS developers have relied on completion handlers and GCD (Grand Central Dispatch) to handle asynchronous operations. With async/await, Swift provides a cleaner way to work with asynchronous code that reads more like synchronous code.

✅ Before:

func fetchData(completion: @escaping (Result<Data, Error>) -> Void) {
    URLSession.shared.dataTask(with: url) { data, _, error in
        if let error = error {
            completion(.failure(error))
        } else {
            completion(.success(data!))
        }
    }.resume()
}

✅ After:

func fetchData() async throws -> Data {
    let (data, _) = try await URLSession.shared.data(from: url)
    return data
}

Best Practices for Using Async/Await in Swift

1. Use Task for Fire-and-Forget Operations

When you don't need a return value or await completion, Task {} is useful:

Task {
    await logUserActivity()
}

2. Structure Background Work with Task Priority


Swift provides task priorities like .background, .userInitiated, etc. to control how tasks execute:
Task(priority: .userInitiated) {
    await performHeavyComputation()
}

3. Make Use of async let for Concurrency

You can run multiple operations in parallel using async let:

async let image = loadImage()
async let profile = loadProfile()
let (img, prof) = await (image, profile)

This helps reduce wait time, especially in UI-heavy apps like social networks or dashboards.

4. Error Handling with try await

Use structured error handling with do/catch to manage exceptions:

do {
    let data = try await fetchData()
    process(data)
} catch {
    print("Error: \(error.localizedDescription)")
}

Common Pitfalls to Avoid

❌ Blocking the Main Thread

Avoid using await inside DispatchQueue.main.async {} unnecessarily—it defeats the purpose.

❌ Overusing Tasks in UI

Creating too many Task {} blocks within SwiftUI views can result in memory leaks or race conditions.

❌ Ignoring Cancellation

Tasks can be cancelled, but many developers forget to handle this. Check for cancellation:
try Task.checkCancellation()

❌ Mixing Old and New APIs Incorrectly

Avoid mixing completion handlers and async/await without bridging properly. Use withCheckedContinuation or withUnsafeContinuation when migrating.

When to Use Async/Await

Network calls (API fetches, file uploads/downloads)
Image and video processing
Data synchronization
Background syncing
CloudKit or Firebase operations

The Strategic Advantage

Using async/await boosts performance, improves code readability, and ensures better app scalability especially for data-intensive mobile apps.

If you're developing enterprise-grade iOS applications or planning to migrate existing apps to modern Swift concurrency, collaborating with a Mobile app development company that specializes in Apple ecosystems and concurrency models can make a significant difference.

Final Thoughts

Swift’s async/await model simplifies concurrency, reduces bugs from nested completion handlers, and enhances maintainability. But it’s only effective when used with discipline

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