将非常见元素从小数组变为大数组，反之亦然

Question

我正在使用subtracting来获取工作正常的非常见元素。

但如果两个数组都有不同数量的元素（计数）

，则无效

像

我有阵列

fileprivate var daysSelected:[Schedule.ScheduleDays] = [] {
    didSet {
        if let array =  equipment.schedules?.map({$0.day}), Set(array).subtracting(Set(daysSelected)).count > 0{
            debugPrint("After updated days ",array)
            daySelectionChanged = true
        } else {
            daySelectionChanged = false

        }
        debugPrint("After updated days ",self.daysSelected)

    }
}

enum ScheduleDays: String {
    case everyday
    case monday
    case tuesday
    case wednesday
    case thursday
    case friday
    case saturday
    case sunday
}

如果array元素较少，则daysSelected返回0

那么是否有任何解决办法从两个数组得到不同的元素，这个数组具有不同的计数而不检查array.count > daysSelected

实施例 假设daysSelected有

  - 0 : App.Schedule.ScheduleDays.tuesday
  - 1 : App.Schedule.ScheduleDays.thursday
  - 2 : App.Schedule.ScheduleDays.friday
  - 3 : App.Schedule.ScheduleDays.saturday
  - 4 : App.Schedule.ScheduleDays.sunday
  - 5 : App.Schedule.ScheduleDays.wednesday
  - 6 : App.Schedule.ScheduleDays.monday

和另一套有

  - 0 : App.Schedule.ScheduleDays.friday
  - 1 : App.Schedule.ScheduleDays.saturday
  - 2 : App.Schedule.ScheduleDays.sunday
  - 3 : App.Schedule.ScheduleDays.tuesday
  - 4 : App.Schedule.ScheduleDays.wednesday

当我

Set(equipment.schedules!.map({$0.day})).subtracting(Set(daysSelected))
0 elements

和

 po Set(daysSelected).subtracting(Set(equipment.schedules!.map({$0.day})))
▿ 2 elements
  - 0 : App.Schedule.ScheduleDays.thursday
  - 1 : App.Schedule.ScheduleDays.monday