我正在尝试过滤一个类的实例数组。我想要一个由类属性之一过滤的新数组。Swift过滤器在此用例中的工作方式无法完全理解。

enum Gender {
    case male,female
}

class Person {
    let name:String
    let gender:Gender
    init(name:String,gender:Gender) {
        self.name = name
        self.gender = gender
    }
}


let people = [Person.init(name: "James", gender: .male),
              Person.init(name: "John", gender: .male),
              Person.init(name: "Sally", gender: .female)
             ]

let males = people.filter( something )