The leaked image of a document detailing the unannounced iPhone 6's storage options reveals that a 128 GB model is indeed on the cars. All models will be powered by NAND flash modules, and it looks like this year Apple is ditching a 32 GB phone model.
Instead, Apple will offer the iPhone 6 in the following flavors - 16 GB, 64 GB and 128 GB.

Toshiba and Hynix are contracted to provide the 16 GB chips. The 64 GB chips are coming from SanDisk, whereas the 128 GB chips are Toshiba branded. |