Issue in understanding compactMap & flatMap

Question

I have gone through from multiple tutorials that flatMap/compactMap is used to flatten an array of array but in my case it's not working or I am not understanding it properly.

let myArray = [["Raja","Kumar", nil,"Waqas"],["UAE","SINGAPORE","dUBAI","HONGKONG"]]
let final = myArray.compactMap{ $0 }

print("Result:\(final)")

OutPut:

Result:[[Optional("Raja"), Optional("Kumar"), nil, Optional("Waqas")], [Optional("UAE"), Optional("SINGAPORE"), Optional("dUBAI"), Optional("HONGKONG")]]

I tried removing nil from the above array but still it's not flattening my array.

Any help would be much appreciated.

Answer 1

compactMap should be used to filter out nil elements from an array of Optionals, while flatMap can be used to flatten out a multi-dimensional array. However, you need to do both.

let final = myArray.flatMap{$0.compactMap{$0}}

print("Result:\(final)")