When the iPhone X arrived with its Face ID system, there was criticism from friends and foe alike.
But that does not faze Schiller, who told the Dutch website Bright that other facial recognition systems "don't work in the ways we need Face ID to work".
"We're very aware that through the years this simple thing, the Home button, that started as the way you click to get to the Home screen, grew into doing so many things for us.
"So for Face ID we needed the best way we know of to enable us to easily unlock our device with our face, in a protected way with the Secure Enclave, and support all these other things. We had to solve all of that."
Schiller said that other things people had tried with face hadn't been anything like that. "Face ID is a very unique implementation."
Asked about the privacy implications of Face ID in view of the fact that data is shared with third-party developers, Schiller denied that any data was shared with third parties.
"First of all, no Face ID data goes to third parties. So what you enrol with Face ID, what you use to unlock your phone, that's an algorithm that is created and encrypted by the Secure Enclave," he said.
"No third party that uses the iPhone camera has your Face ID data. We did create an API so developers can use the cameras to track facial movements, to do things like wrap stickers on your face (like Snapchat, ed.) That’s different than Face ID. They don’t have all the access to the data that Face ID has for that."