[mendocino]

The GPU is a design from Imagination Technologies, the CPU is an Apple design. What part of the SoC is "mostly designed by ARM"?

[Mikeb85]

The CPU. Apple licenses ARM's reference designs, then creates an SoC around that.

[mendocino]

The last SoC where this has been the case is the A5 (using the the ARM Cortex-A9 MP). The Apple A6 and A7 don't use ARM cores and neither does Qualcomm in their Snapdragon SoCs.

[seabrookmx]

ARM just comes up with the instruction set. The cores are still designed by Samsung, Qualcomm, NVidia, etc.