At this rate Samsung was also in production at the time...
The fact that they have a customer is an indication that they have at least some yields, i would call them mediocre if at 10% and good enough if at 20%, indeed that was the number posted in this very thread, now let s look at the economics.
Assuming 60mm2 chips are fabbed they would get about 1000 chips out of a waffer, at 10% yields, that is 100 chips, the cost is such that it is not worth to produce for others but since Samsung, like Intel, has a finished product that leverage the CPUs margins they could use it in high end phones at a cost of about 70-80$/chip.
For Apple it s different, they need at least 200 chips/waffer to get to 35-40$/chip, although high this cost can easily be amortized by Apple since, like Samsung and Intel, they have the mean to sell it within a high margins item, the very fact that they have this customer imply yields that are at least 20%.