更改初始數組值Swift

Question

我正在嘗試更改初始數組的值，但是我不確定如何做到這一點。

例：

var players = ["Peter", "John", "Michael"]
var rules = ["\(players.randomElement()!) has to run", "\(players.randomElement()!) is the best"]

players.removeAll()
players.append("Gina", "Martin")
print(rules)

然后我要打印Gina或Martin。

Answer 1

這是因為規則不知道玩家改變了他們的價值觀。 您需要在更改播放器后重新設置規則或打印播放器（而不是規則）

Answer 2

如果希望每次訪問rules都選擇一個新player則需要將rules設為計算屬性。

var players = ["Peter", "John", "Michael"]
var rules: [String] {
    return ["\(players.randomElement()!) has to run", "\(players.randomElement()!) is the best"]
}

players.removeAll()
players.append("Gina", "Martin")
print(rules)

或者，如果您只是想在players器更新時基於新players自動刷新rules ，則可以向players器添加屬性觀察器。

var rules = [String]()
var players = ["Peter", "John", "Michael"] {
    didSet {
        if players.count > 0 {
            rules = ["\(players.randomElement()!) has to run", "\(players.randomElement()!) is the best"]
        } else {
            rules = []
        }
    }
}

rules = ["\(players.randomElement()!) has to run", "\(players.randomElement()!) is the best"]
print(rules)
players.removeAll()
players.append(contentsOf: ["Gina", "Martin"])
print(rules)