arrays - 确定字符串来自哪个数组

Question

我有 3 个动物数组:

let mammals = ["Dog", "Cat", "Bear"]
let fish = ["Clownfish", "Seahorse", "Scorpion Fish"]
let reptiles = ["Chameleon", "Snake", "Lizard"]

一个按钮随机生成一个动物，然后将它附加到一个 allAnimals 数组中。我希望能够确定字符串(动物)来自哪个数组。

我试过用

allAnimals.contains()

然而，它显式地接受一个 var 作为参数。我可以做 allAnimals.contains("Seahorse") 就好了。但我需要能够检查所有数组。

我还尝试遍历数组。

for i in allAnimals {
  if i.contains(mammals){ print("Came from the Mammal array") }
  else if i.contains(fish){ print("Came from the Fish array") }
  else if i.contains(reptiles){ print("Came from the Reptiles array") }
}

抛出错误:

Cannot convert value of type '[String]' to expected argument type 'String'

如何确定随机字符串来自哪个数组？

Answer 1

您可以用不同的动物类型定义一个枚举，并构造该枚举动物类型的数组，其中枚举中每个案例的关联值 (String) 给出了动物的详细信息。

例如

enum Animal: CustomStringConvertible {
    case mammal(String)
    case fish(String)
    case reptile(String)

    var description: String {
        switch self {
        case .mammal: return "Mammal"
        case .fish: return "Fish"
        case .reptile: return "Reptile"
        }
    }

    var species: String {
        switch self {
        case .mammal(let s), .fish(let s), .reptile(let s): return s
        }
    }
}

示例用法:

let mammals = ["Dog", "Cat", "Bear"].map(Animal.mammal)
let fish = ["Clownfish", "Seahorse", "Scorpion Fish"].map(Animal.fish)
let reptiles = ["Chameleon", "Snake", "Lizard"].map(Animal.reptile)

let allAnimals = [reptiles[2], mammals[1]]

for animal in allAnimals {
    print("\(animal.species) is a \(animal)")
} /* Lizard is a Reptile
     Cat is a Mammal     */