In this chapter, we applied a CNN for the task of recognizing facial expressions. Using this, we could infer the emotional state of a given face. As usual, we again spent the majority of our time understanding the required input for the model and implementing the functionality to facilitate this. But, in doing so, we uncovered some important considerations when developing intelligent applications; the first is the explicit awareness of using either an end-to-end solution or a multi-step approach, with the multi-step approach being the most common one you will use.

This essentially means you, the designer and builder of intelligent applications, will be building data pipelines consisting of many models, each transforming the data in preparation for the next. This is similar to how deep networks work but provides greater flexibility. The second consideration is highlighting the availability of complementary frameworks available on iOS, in particular the Vision framework. It was used...