Interface builder (and now storyboards) have allowed WYSIWYG iOS interface layouts since 2008. There are definitely more dependencies and interrelation between a native app vs web app, but there is definitely a high-quality layout engine that makes basic formatting tasks easy.
The basics are definitely easy. A lot of apps need more than the basics; even changing between landscape and portrait can be tricky and more complex that a simple autoresizing mask can handle (I would know, since I'm neck-deep in developing an iPad app that needs this kind of complex layout and needs to support all orientations).
