RSWeb is utility code — all Swift — for downloading things from the web. It builds a Mac framework and an iOS framework.
See OneShotDownload for a top-level download function that takes a URL and a callback. The callback takes Data, URLResponse, and Error parameters. It’s easy.
See DownloadSession and DownloadSessionDelegate for when you’re doing a bunch of downloads and you need to track progress.
HTTPConditionalGetInfo helps with supporting conditional GET, for when you’re downloading things that may not have changed. See HTTP Conditional Get for RSS Hackers for more about conditional GET. This is especially critical when polling for changes, such as with an RSS reader.
MimeType could use expansion, but is useful for some cases right now.
MacWebBrowser makes it easy to open a URL in the default browser. You can specify whether or not to open in background.