With the 5.5 inch screen of the iPhone 6 Plus, typing is quite difficult with the current, and nonadjustable location of the keyboard at the bottom of the screen. Apple should add the ability to slide the keyboard up the screen just a bit to make typing much more functional, whether typing with one hand or two. Build the functionality and UI exactly like it currently exists on the iPad, when using the undock function usually utilized with the split keyboard, or, more relevant here, on its own.
When in landscape, the ability to actually split the keyboard just like current iPad should be added into iOS, but moving the keyboard location higher on the screen will not be as necessary like when in portrait. However, first and foremost, fix the glaring UX blunder with the keyboard stuck at the bottom of the screen when in portrait, the phone wants to fall forward when typing.