It's hard to make good form fields on about any smaller screen. I've always thought the best form field is the one you delete because you don't absolutely have to have that piece of information. I agree with the below. If it's mostly impossible to make a great form, what should we do? Aleksandar has some tips we can follow.
I have built so many forms in the last 5 years, I honestly believe it’s impossible to create a forms library that will work out of the box if you care about design consistency across your app
Trouble with form fields in iOS apps by Aleksandar Vacić