Symptoms appear to be systemic or vascular. Look for damage elsewhere.
Could be herbicide. Was the lawn recently sprayed? Broadleaf herbicides usually cause leaf curling, although your leaves do not seem to look exactly like that.
It would be helpful if you explained a bit about what kind of weather you have been having, and what is normal.
Also, I am a bit confused. "Formed fruit" and "flowers present" seem to be mutually exclusive events. Flowers preceed fruit on apple trees, so I expect that any flowers are naturally wilting.
NOT that I pretend to be an expert on fruit trees. Maybe somebody that actually knows about these things will pipe up and give a good guess.
