Update README.md for async/await

[dnadoba]

We want to highlight the new async/await API in the README.

• add new examples for async/await but keeps old examples for SwiftNIOs EventLoopFutures
• change URL used in examples from swift.org to apple.com because swift.org doesn't respect that we don't support compression by default which results in gibberish output if examples are run by users.
• increase recommended Xcode Version to 13.2 and Swift Version to 5.5.2
• increase recommend AsyncHTTPClient version to 1.9.0

[fabianfett]

backpressure has nothing todo with the loop, and I don't think we should explain it here. It just works ;)

[dnadoba]

I think we should mentioned this at least somewhere. AFAIK, this is not documented anywhere or am I missing something? This is a really great feature and we should definitely mention it.

[Lukasa]

I'm with @dnadoba that we should mention it, but I'm with @fabianfett that I don't think we need to explain it: it just works. In this case, maybe at the top of the loop I'd change that comment to something like:

// asynchronously iterates over all body fragments
// this loop will automatically propagate backpressure correctly

[fabianfett]

close AHC?

[dnadoba]

The full example has the shutdown():

async-http-client/Examples/StreamingByteCounter/StreamingByteCounter.swift

Lines 25 to 52 in 3405d11

	let httpClient = HTTPClient(eventLoopGroupProvider: .createNew)
	do {
	let request = HTTPClientRequest(url: "https://apple.com")
	let response = try await httpClient.execute(request, timeout: .seconds(30))
	print("HTTP head", response)
	// if defined, the content-length headers announces the size of the body
	let expectedBytes = response.headers.first(name: "content-length").flatMap(Int.init)
	var receivedBytes = 0
	// Asynchronously iterates over all body fragments.
	for try await buffer in response.body {
	// For this example, we are just interested in the size of the fragment
	receivedBytes += buffer.readableBytes
	if let expectedBytes = expectedBytes {
	// if the body size is known, we calculate a progress indicator
	let progress = Double(receivedBytes)/Double(expectedBytes)
	print("progress: \(Int(progress * 100))%")
	}
	// in case backpressure is needed, all reads will be paused until returned future is resolved
	}
	print("did receive \(receivedBytes) bytes")
	} catch {
	print("request failed:", error)
	}
	// it is important to shutdown the httpClient after all requests are done, even if one failed
	try await httpClient.shutdown()

We would need to nest it in a do catch to be correct but I'm fine with it if you want to add it. I didn't add it because the old one also has no shutdown. However, I'm just discovering that the old examples doesn't create an AsyncHTTPClient, it just assumes that there is one. I see two options:

• remove HTTPClient creation
• or add shutdown

WDYT?

[Lukasa]

I think add the shutdown and nest in a do catch.

[Lukasa]

So much nicer! 🎉

[Lukasa]

I'm with @dnadoba that we should mention it, but I'm with @fabianfett that I don't think we need to explain it: it just works. In this case, maybe at the top of the loop I'd change that comment to something like:

// asynchronously iterates over all body fragments
// this loop will automatically propagate backpressure correctly

[Lukasa]

I think add the shutdown and nest in a do catch.

[fabianfett]

Awesome!

[glbrntt]

Looks good, I left two tiny nits though

[glbrntt]

nit, space makes it more readable:

Suggested change

	let progress = Double(receivedBytes)/Double(expectedBytes)
	let progress = Double(receivedBytes) / Double(expectedBytes)