更改初始数组值Swift

Question

我正在尝试更改初始数组的值，但是我不确定如何做到这一点。

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

这是因为规则不知道玩家改变了他们的价值观。 您需要在更改播放器后重新设置规则或打印播放器（而不是规则）

Answer 2

如果希望每次访问rules都选择一个新player则需要将rules设为计算属性。

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器更新时基于新players自动刷新rules ，则可以向players器添加属性观察器。

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)