What is Metal?
Metal is a low level GPU programming framework for IOS. It is developed by Apple since 2014 and written in C++. Metal has been released in 2014 and has been upgraded to Metal 2 in WWDC 2017 with lots of interesting additions specifically for Machine Learning techniques.
While high-level APIs like OpenGL are still used in many contexts, there's been a definite trend toward low-level APIs that can take advantage of the massive advancements in GPU speed.
Advantages of Metal
Metal is specifically developed for speed enhancement and work with Apple's hardware architecture. It allows you to take advantage of the Apple's hardware directly rather than relying on the API to handle it for you. By doing so, It will allow you to achieve much higher performance than the high level API. Metal is also designed for building upon an efficient low-overhead architecture.
Disadvantages
Metal is supported for only new Apple Device. For cross platform support, we still need to use openGL. As Metal is appear to be a new framework, there is less in learning material online, so It's kinda hard for newbie like me to start exploring about this new GPU programming framework.
Metal vs OpenGL
OpenGL is developed for the flexibility. It's one of the high-level GPU programming framework while Metal is a low-level GPU programming framework.
Metal provide direct-access to the GPU, so that we can maximize the graphics and compute potential of your app on IOS MacOS and tvOS.
Metal is developed by Apple and they know exactly which chip they are using for their GPU programming, so that they can optimize the framework to work specifically and directly with the chip.
Conclusion
Metal is a great API in this 21st century to write code and ship the applications with. It's easy to use and beats OpenGL in every single aspect.
Along with this article, I also create a sample project to draw a simple triangle.
https://github.com/phanithken/MetalSampleTriangle