So the core issue is the usage of shared constants for Interface Builder files.
Preprocessor macros can only be used in files that are run through the C preprocessor — essentially just your code. So you can't use macros to implement shared constants for IB files. Similarly you cannot use actual constants that you define in your code files.
What you can do, however, is to create a custom UITextField
(or any UIView
for that matter) subclass, set your constant values (or define any other custom behavior) in the subclass implementation, and then select this custom class name in Interface Builder's Identity Inspector -> Custom Class section for all of your text field elements.