What is a Singleton?

The Singleton design pattern keeps the instantiation of a class to a single instance. Controversial but convenient, Singletons are something you will most definitely encounter in your life as a developer.
👍Singletons are very quick to implement and can make accessing an object easy.
👍Better than static classes, they can leverage polymorphism, cache values, and have their instances swapped out.
👍They require low memory usage, low latency, and only need one initialization.
👍In Unity, it offers better performance then FindObjectOfType.
👎Controlling initialization order across Singletons can become messy very quickly.
👎Deviates from the single responsibility principle.
👎Promotes mass coupling to a single instance.
👎It can be difficult to refactor, especially if you need to change its behavior in a different context.
👎In Unity, it is difficult to track the lifecycle of the Singleton MonoBehavior.
👎It's not always easy to subclass and extend.
👎Easy to abuse with many singletons and have limited flexibility in your codebase.
✅Do I recommend Singletons? Well, it depends...
✅Is your project small? Do you have time constraints? Will your class change in the future, or will it most likely always behave the same? e.g. logging system.
​✅Singletons are not the cleanest or most flexible system, but they are convenient and quick to implement.
✅In Unity, Singleton MonoBehaviors can swap instances depending on what scene or prefab is loaded.
🚀Beware overuse, understand the limitations, and use it at your own discretion.
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➡️Free Unity Tools: https://www.mefirstgames.com/hierarchy-comments.html 

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