…why would anyone want to have Dvorak on a mobile device?!? Actually, I only care about it in the iOS Simulator, when I’m using it on a computer with a real-live hardware keyboard.

In OS X’s Simulator (v9.3), launch the Settings app from the home screenfootnote:[which you can get to quickly by pressing Command+Shift+h], then navigate through all these menus: General > Keyboard > Hardware Keyboard > English > Dvorak.