I use Pages quite a lot on my iPad as part of my job. One irritating issue is that I can’t add words to its dictionary. In fact, this dictionary is shared amongst all apps and nowhere can you add words. (Note that I’m talking here about the red underlining of words as misspelled; I’m not talking about autocorrect, which can be easily trained by typing the ‘incorrect’ word several times in succession.)
For me the problem isn’t so much not being able to add words to the dictionary as it is removing all the red underlining, which is truly distracting when working. However, I want to retain the live spell checking because it’s useful.
I found a solution. Open the Contacts app and create a new contact. Then type the words you want the device to learn into the first name and surname fields. Close and reopen your doc in Pages and suddenly the words won’t be underlined as misspelled any longer.
Alas, this tip isn’t perfect. Plurals of the words won’t be recognised, for example, so must be added individually.
But this works well enough for me, usually to enter proper nouns that my iPad and iPhone simply don’t know. Note that if you’ve a Mac you can create the contact there and it’ll sync automatically with your iDevices via iCloud.
I hesitate to post tips like this because it feels like a problem that Apple will surely fix sooner rather than later. Alas, people have been waiting for several years now. The whole text entry system on iOS needs attention but Apple seemingly refuses to do so.