From the UIKit documentation:
Appearance of Picker Views (Programmatic)
You cannot customize the appearance of picker views.
Question
I couldn't find it anywhere...
I have the option to expand a bit the UIPickerView to show more than 5 (almost 7) rows it displays.
numberOfRowsInComponent is usually 20-30 in my case so if I am able to show the user some more, it is nicer
I can't to that?
Solution
From the UIKit documentation:
Appearance of Picker Views (Programmatic)
You cannot customize the appearance of picker views.