iOS's Spelling Predictive Analysis - for bilingual writers?
You have to activate the corresponding keyboards on Settings > General > Keyboards > Keyboards. Then when writing on each language, tap the world icon to the left of the space bar to switch between languages. The spelling check, prediction and dictionaries will be independent. The voice recognition also switches with it.



If you keep the globe pressed, a list will pop up, and you can chose the language directly.



Esto me da una buena excusa para escribir en español (mientras no exista un "Pregunta Diferente").



As you see from the screen-grab, no spelling suggestions are made to my Spanish phrase because I had the Spanish keyboard activated while writing it. However, if I go back and tap on it with the English keyboard activated, it will get red all over.