How to... Swift

I think it's difficult to memorize code fragments or procedures, so I want to describe these code fragments and procedures that I use in my Swift projects to use them when ever I want... and maybe it would be useful for every Swift developer. I hope so.

My native language is Spanish and I am not fluent in English yet, so it's possible you find some mistakes, please be kind and tell me to fix them.

If you want to collaborate you are welcome!