While I assume it's the case that the tool stack doesn't support anything more advanced in the way of an IDE than a texteditor syntax highlight plugin; the article itself is talking about the lack of a GUI library; because SwiftUI is a thin wrapper on top of native Apple controls; and doesn't have any sane porting path to Windows. (Just like there's no sane native way to do WinForms/WPF with .net on *NIX.)
Did you ever see history portrayed as an old man with a wise brow and pulseless heart, weighing all things in the balance of reason? Is not rather the genius of history like an eternal, imploring maiden, full of fire, with a burning heart and flaming soul, humanly warm and humanly beautiful? --Zachris Topelius Training a telescope on one’s own belly button will only reveal lint. You like that? You go right on staring at it. I prefer looking at galaxies. -- Sarah Hoyt