Automatic Language switch to predict words
The idea is that the typing language is detected from the first words typed and then to predict in that language. The current used language should be displayed, and the user would be able to switch to any other installed language. A setting could be added to choose between auto detection and pre defining the default language.
This way the other dictionaries would be active only when needed. The occasional word in another language could be chosen after quick switching the current language, and the suggestions would be refreshed to match the new language.
You can write in up to 3 languages simultaneously with SwiftKey.
Enable your languages in SwiftKey settings→Languages&Layouts and then SwiftKey should offer you predictions in the relevant language as you type.
I think this would be better solved by giving words in the same language as the previous word/words higher priority when autocorrecting or predicting. At least initially, I'd still want it to learn when I borrow english words while typing swedish for example.
Christian Barkholt Muller commented
I like the bilingual option as it is. Personally I often switch between Danish and English - also within the same text - and it would be very annoying if I had to press a button every time I change language. Instead it works fantastically now, where it automatically predicts words from both language based on my own writing habits.
Please don't do this. I like SwiftKey precisely because I can just flow and it will just recognize if it's English, French or Spanish and I don't need to switch languages
Jan Andersen commented
It would work, to a degree. I like the idea of being able to suppress/disable a dictionary. But I think I need to also be able to do manually. I use 3 different languages, English, Danish and Swedish. Automatic detection will work for English, but Danish and Swedish are very similar so you will need more than one word for the prediction. Choosing the dictionary based on keyboard layout could work, except SwiftKey has a combined English/Danish layout.