For iPhone User please try "AEI Keyboard Note" App. (This app is Free)

What is Good about AEI Keyboard
- Only One Push to input Vowel (letter).
- Less than Two Push to input Alphabet. (any letter)
- Input faster with Two Thumbs.

Original Spanish Keyboard for iPhone & iPad
* With Arrow Keys
* Word predict.
* Easy to input “¿¡áéíóúüñÁÉÍÓÚÜÑ"
* iPad Special Ten Keys like PC Ten Keys.
* Ideal Key for iPhone (It's called AEI Keyboard)

Useful keyboard Settings (tap"tools")
You can turn off Key Sound from it.

Please add this Keyboard from iOS Setting and switch "Allow Full Access"

Note : This app may not work on Old Apps.