这种函数能够返回枚举的计数。

斯威夫特2:

func enumCount<T: Hashable>(_: T.Type) -> Int {
    var i = 1
    while (withUnsafePointer(&i) { UnsafePointer<T>($0).memory }).hashValue != 0 {
        i += 1
    }
    return i
}

斯威夫特3:

func enumCount<T: Hashable>(_: T.Type) -> Int {
   var i = 1
   while (withUnsafePointer(to: &i, {
      return $0.withMemoryRebound(to: T.self, capacity: 1, { return $0.pointee })
   }).hashValue != 0) {
      i += 1
   }
      return i
   }

当然，它不是动态的，但在很多情况下，你可以在Enum中添加一个静态的var

静态变量计数:Int{返回7}

然后使用它作为EnumName.count

以下方法来自CoreKit，与其他人建议的答案相似。这适用于Swift 4。

public protocol EnumCollection: Hashable {
    static func cases() -> AnySequence<Self>
    static var allValues: [Self] { get }
}

public extension EnumCollection {

    public static func cases() -> AnySequence<Self> {
        return AnySequence { () -> AnyIterator<Self> in
            var raw = 0
            return AnyIterator {
                let current: Self = withUnsafePointer(to: &raw) { $0.withMemoryRebound(to: self, capacity: 1) { $0.pointee } }
                guard current.hashValue == raw else {
                    return nil
                }
                raw += 1
                return current
            }
        }
    }

    public static var allValues: [Self] {
        return Array(self.cases())
    }
}

enum Weekdays: String, EnumCollection {
    case sunday, monday, tuesday, wednesday, thursday, friday, saturday
}

然后你只需要调用weekdays。allvalues。count。

这种函数能够返回枚举的计数。

斯威夫特2:

func enumCount<T: Hashable>(_: T.Type) -> Int {
    var i = 1
    while (withUnsafePointer(&i) { UnsafePointer<T>($0).memory }).hashValue != 0 {
        i += 1
    }
    return i
}

斯威夫特3:

func enumCount<T: Hashable>(_: T.Type) -> Int {
   var i = 1
   while (withUnsafePointer(to: &i, {
      return $0.withMemoryRebound(to: T.self, capacity: 1, { return $0.pointee })
   }).hashValue != 0) {
      i += 1
   }
      return i
   }

创建如下答案所示的静态allValues数组

enum ProductCategory : String {
     case Washers = "washers", Dryers = "dryers", Toasters = "toasters"

     static let allValues = [Washers, Dryers, Toasters]
}

...

let count = ProductCategory.allValues.count

当您希望枚举值时，这也很有用，并且适用于所有Enum类型

enum WeekDays : String , CaseIterable
{
  case monday = "Mon"
  case tuesday = "Tue"
  case wednesday = "Wed"
  case thursday = "Thu"
  case friday = "Fri"
  case saturday = "Sat"
  case sunday = "Sun"
}

var weekdays = WeekDays.AllCases()

print("\(weekdays.count)")