Experimental `functions._invokeWithStreamedResponse` never yields data

[kirkbyo]

Bug report

Describe the bug

When utilizing the experimental functions. _invokeWithStreamedResponse method (introduced in #346), the returned AsyncThrowingStream never yields any data to the consumer.

let events = supabase.functions._invokeWithStreamedResponse("some-sse-edge-function", options: options)
for try await data in events {
   // never executed
}

To Reproduce

Initialize _invokeWithStreamedResponse with an edge-function configured to send a text stream (e.g. the Deno SSE template should suffice).

Expected behavior

As bytes are decoded from the underlying NSURLSession they are yielded to the consumer.

System information

• OS: macOS 14.4.1
• Version of supabase-swift: 2.13.2
• iOS version: 17.0.1

Additional context

The current implementation of _invokeWithStreamedResponse creates a session.dataTask with a callback:

supabase-swift/Sources/Functions/FunctionsClient.swift

Lines 201 to 217 in fa8db0c

	let task = session.dataTask(with: urlRequest) { data, response, _ in
	guard let httpResponse = response as? HTTPURLResponse else {
	continuation.finish(throwing: URLError(.badServerResponse))
	return
	}
	guard 200 ..< 300 ~= httpResponse.statusCode else {
	let error = FunctionsError.httpError(code: httpResponse.statusCode, data: data ?? Data())
	continuation.finish(throwing: error)
	return
	}
	let isRelayError = httpResponse.value(forHTTPHeaderField: "x-relay-error") == "true"
	if isRelayError {
	continuation.finish(throwing: FunctionsError.relayError)
	}
	}

however, it is also specifying a URLSession delegate which is responsible for yielding data:

supabase-swift/Sources/Functions/FunctionsClient.swift

Line 197 in fa8db0c

let session = URLSession(configuration: .default, delegate: delegate, delegateQueue: nil)

According to the docs, if a dataTask is specified with a callback, then the delegate is never used, which would explain why values are never yielded:

By using the completion handler, the task bypasses calls to delegate methods for response and data delivery, and instead provides any resulting NSData, URLResponse, and NSError objects inside the completion handler. Delegate methods for handling authentication challenges, however, are still called.

Patching the library to no longer use the callback resolved my issue: kirkbyo@70959a3

[grdsdev]

Thanks for reporting @kirkbyo

Feel free to open a PR with your fix.