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Color Keyboard will allow you to change the theme of the keyboard.

IKeywi will add an extra row to the keyboard which you can customize.
 
Visual or function?

For visual, use ColorKeyboard, ShowCase (shows lower cases)

For function, use SwipeSelection
 
best Swype keyboard is probably TouchPal. it will show up in Chinese at first but you can change it to English when adding the keyboard
 
OK I think I was a bit too open.

So totally functional, just to make it faster to type.
Must be fully integrated so replaces the standard keyboard.
iPhone 5 compatible.
 
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