Swift：省略記法を使わないflatMap，compactMap

flatMap

let array: [[String]] = [["apple", "banana"], ["grape", "peach"]]

let flatArray = array.flatMap { (innerArray) -> [String] in
    return innerArray
}

Swift.print(flatArray)
// -> ["apple", "banana", "grape", "peach"]

compactMap

let array: [String?] = ["apple", "banana", nil, "grape"]

let nonNilArray = array.compactMap { (str) -> String? in
    return str
}

Swift.print(nonNilArray)
// -> ["apple", "banana", "grape"]

私は$0を使う省略記法あまり好きではないです...