Relations between Apple and Samsung has been tenuous at best and it is no secret that Apple is trying as hard as possible to avoid using Samsung for parts or manufacturing. Unfortunately, its current generation A7 SoC is presently manufactured by Samsung.
However, the latest reports to emerge from Taiwan suggests that TSMC is now the major partner for Apple in the production of its new "A8" SoC. This new SoC is claimed to be a 64-bit quad-core part built using a 20nm manufacturing process and will offer quad-core graphics as well.
The fact that Apple has been seeking out other fab partners outside of Samsung is well-documented and here is where reports differ. Some suggest that while both Samsung and TSMC were expected to split the production load, Samsung has apparently been dropped due to low yields.
Others suggest that while TSMC is preferred, there are concerns over its ability to meet Apple's demand. As such, Samsung will still be kept on but used in a more limited fashion should TSMC fail to meet demand.