Vector assets for iOS are PDFs. Not being able to import existing assets directly sucks.
I would like to understand more about your workflow. What are you trying to achieve and what prevents you doing with the latest XD version?
I would like to be able to use vector assets instead of png pre-made assets. Especially since our company has pre-made brand assets for use in our apps (icons, logos, app icons, etc). These live in our shared adobe library but yet I cannot use them inside XD. Having support for importing PDFs would be nice especially from my creative cloud library.
Jacob Scarani commented
Just drag and drop PDF documents into your design.
Can be used for resumes, flyers, etc.