The example is present in Examples/FastStyleTransferIOS.
Before you run anything you need to download two files protobuf.a and libtensorflow-core.a and move them to TensorFlowSharp/TensorFlowSharp.iOS folder. They are the two tensorflow compiled static libraries for iOS.
Link:
https://www.dropbox.com/sh/2do9daqnadubi6m/AAAPd3E7koUNCCrO-aXhRVeVa?dl=0
Note: To compile the static libraries yourself check my other fork of tensorflow itself.
https://github.com/AndreJFBico/tensorflow