a sample on using flatMap on an array of Optionals.

OptionalArrayFlatMapSample.swift

let unwrapFlatMapCount = sailorNames.flatMap { name -> String? in
		return name
}.count

let otherOptionalFlatMapCount = sailorNames.flatMap { name -> Int? in
	return name?.hashValue
}.count

let otherNormalFlatMapCount = sailorNames.flatMap { name -> Int in
	return name?.hashValue ?? 0
}.count

print("Unwrap flatMap count: \(unwrapFlatMapCount)") // will print 4
print("Other optional flatMap count: \(unwrapFlatMapCount)") // will print 4, too
print("Other `normal` flatMap count: \(otherNormalFlatMapCount)") // will print 6