File Handle Not Closed (ARCH9080)

Key swift.performance.file-handle-not-closed · Severity error · Category performance

Flags FileHandle / InputStream / OutputStream opened without close() (or a defer that closes it) on the same path.

Incorrect

let h = try FileHandle(forReadingFrom: url)
let data = h.readDataToEndOfFile()

Correct

let h = try FileHandle(forReadingFrom: url)
defer { try? h.close() }

Fix

Close the handle in a defer right after opening it.