What is the difference between `async/await` and GCD (Grand Central Dispatch)?

Answer: Both manage concurrent work, but async/await (introduced in Swift 5.5) is structured and compiler-checked, while GCD is unstructured and callback-based.

	async/await	GCD
Style	Structured	Unstructured
Readability	Linear code	Nested callbacks
Error handling	throws / try	Manual
Cancellation	Automatic (Tasks)	Manual
Thread safety	Enforced by actors	Manual

Code Example:

// ❌ GCD — nested, harder to read and reason about
func loadUser(completion: @escaping (User?) -> Void) {
    DispatchQueue.global().async {
        let user = fetchFromNetwork()
        DispatchQueue.main.async {
            completion(user)
        }
    }
}

// ✅ async/await — reads like synchronous code
func loadUser() async throws -> User {
    let user = try await fetchFromNetwork()
    return user
}