How to Send Array Event Parameters?

So this seems like a simple question, but my team has had troubles understanding what is expected from an array as an Event Property and how to implement it in Android and iOS. 

Are we passing a JSON Array? Is it in a string structure and Amplitude will parse that? An example for both iOS and Android would be great here, since we’ve never been able to get it right according to the Data Dashboard. 

Also, from demos I’ve seen, the arrays will be parsed and broken down, so you’ll never see the array “[ ]” in any of the parameter values, is this what I should expected? If this is the case, is there a way to see the spread of array values without having to choose all different combinations of the array values?

So in short, what does Amplitude expect, and what should we expect here? 

Thanks in advance.