iKeywi is a tweak which can let you customize the keyboard on your iPhone.

Features:
> Adds an extra row to your keyboard
> Supports all languages (*)(**)(***)
> Supports both portrait and landscape mode
> Set keys as cursor mover and undo/redo function
> Compatible with iPhone 4/4s/5/5s/5c/6 and 6 plus
> ...and more!

Compatible With:
> HandyKey
> ShowCase
> SwipeSelection

Note:
* Not support: Kana(かな入力), Korean 3x3 (10키), Pinyin 3x3(十键拼音), Strokes(笔画) and Handwriting(手寫).
** Zhuyin(注音)