swift - 无法分配给 Swift 类型的不可变表达式

Question

我看过几个类似的 SO 问题，但没有太多帮助，

我正在尝试使用 updateDailyTimes 函数使用 timesArray 更新星期一的 availabilityTimes

availabilityTimes 和 timesArray 示例

 var availabilityTimes = [
         "Monday": [ "available" : true,
                     "times": [
                         ["startTime": "9:00 am", "endTime": "1:30 pm" ],
                         ["startTime": "2:30 pm", "endTime": "6:00 pm" ],
                         ["startTime": "7:30 pm", "endTime": "9:00 pm" ]
                     ]
         ],
         "Tuesday": [ "available" : true,
                     "times": [
                         ["startTime": "9:00 am", "endTime": "6:00 pm" ]
                     ]
                    ]
          ]




var timesArray = [
                    ["startTime": "9:00 am", "endTime": "1:30 pm" ],
                    ["startTime": "2:30 pm", "endTime": "6:00 pm" ],
                    ["startTime": "7:30 pm", "endTime": "9:00 pm" ]
                  ]

这是我的代码，当我调用下面的函数时，我在代码行 value 中收到一条错误消息 cannot assign to immutable expression of type [[String : String]] ["times"] as [[String : String]] = timesArray

func updateDailyTimes(day: String, timesArray: [[String:String]]){

    guard var updatedTimes = self.availabilityTimes as? [String: AnyObject] else{
        return
    }

    for (key, var value) in updatedTimes {

        if key == day{
            for (key1, value1) in value as! [String : AnyObject]{
                if key1 as String == "times" {
                    value["times"] as [[String : String]] = timesArray // I get an error message in this line
                }
            }

        }
    }
}

Answer 1

根据我的评论，我指的是用于开始和结束时间的自定义结构 Times 和具有所需属性的结构 DailyTimes 以及用于更新 Times 数组:

struct Times {
    let start : String
    let end : String
}

struct DailyTimes {
    let weekday : String
    var available : Bool
    var times = [Times]()

    mutating func update(times : [Times]) {
        self.times = times
    }
}

现在创建 availableTimes 字典:

var availableTimes = ["Monday" : DailyTimes(weekday: "Monday", available: true, times: [Times(start: "9:00 am", end:"1:30 pm"),
                                                                                        Times(start: "2:30 pm", end:"6:00 pm"),
                                                                                        Times(start: "7:30 pm", end:"9:00 pm")]),
                      "Tuesday" : DailyTimes(weekday: "Tuesday", available: true, times: [Times(start: "9:00 am", end:"6:00 pm")])]

和 timesArray 数组:

let timesArray = [Times(start: "9:00 am", end:"1:30 pm"),
                  Times(start: "2:30 pm", end:"6:00 pm"),
                  Times(start: "7:30 pm", end:"9:00 pm")]

由于 Monday 的 Times 数组已经包含 timesArray 的值，让我们更新 Tuesday

availableTimes["Tuesday"]?.update(times:timesArray)

终于证明了

print(availableTimes["Tuesday"]?.times)

另一个改进可能是使用 DateComponents 而不是 String 来表示时间。