拉风的咖菲猫
12345678func calc(x: Int, y: Int, callback: @escaping (Int, Int) -> Int) -> Int { return callback(x, y)} let add = calc(x: 1, y: 2) { return $0 + $1 }let reduce = calc(x: 4, y: 3) { x, y in return x - y } print(add, reduce)