A quick update on the upcoming Yongnuo lenses for Nikon F mount from Petapixel – 50mm f/1.8 and 35mm f/2 versions will be released later this year:
“Yongnuo tells PetaPixel that it’s aiming to release a 50mm f/1.8 prime lens for Nikon cameras in July 2015, followed by a 35mm f/2 lens for Nikon DSLRs in October 2015. Another lens may be unveiled in December 2015. No word yet on pricing or specs – we may have to wait until the lenses are officially out to get those details.” (source)
Yongnuo is already producing several lenses (clones) for Canon DSLR cameras.