Target Metal Performance Shader (MacOS and iOS)
The Metal framework is a low-level Apple framework to access GPU-accelerated graphics and compute features.

In particular Metal provides off-the-shelf functions for convolutional neural network.

Docs:
- reference: https://developer.apple.com/documentation/metalperformanceshaders
- comparison with Apple Accelerate Basic Neural Network: http://machinethink.net/blog/apple-deep-learning-bnns-versus-metal-cnn/

Cool videos:
![image](https://cdn-images-1.medium.com/max/1600/1*YAqDD4CGAIy-WYx8HITPPA.gif)
![image](https://cdn-images-1.medium.com/max/1600/1*nbXMexCVMcNfgbdW1u_p1w.gif)
