Await In Loop (ARCH9030)

Key swift.async.await-in-loop · Severity info · Category async

Flags await inside a for-in loop over independent items - the work is serialised. A while / repeat loop retries until something succeeds and cannot be parallelised.

Incorrect

for id in ids {
    results.append(try await fetch(id))
}

Correct

try await withThrowingTaskGroup(of: Item.self) { group in
    for id in ids { group.addTask { try await fetch(id) } }
    for try await item in group { results.append(item) }
}

Fix

Use a task group (or async let) to run the iterations concurrently.