Another sample on using flatMap on an array of Optionals.

OptionalArrayFlatMapSample_2.swift

let duckSailors = ["Daffy", "Donald", "Howard"]
let sealSailors = ["Manatee", "Moby"]

let otherSailors = [duckSailors, sealSailors]

let flattenedSailors = otherSailors
.flatMap { nameArray -> [String] in
	return nameArray
}
	
print("Flatten Sailor names: \(flattenedSailors)")

flattenedSailors.forEach { name in
	print(createGreetings(sailorName: name))
}