枚举

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

    }
    var dir = Direction.east;
    func test() {
        switch dir {
        case .north:
            print("north")
        case .west:
            print("west")
        case .south:
            print("south")
        case .east:
            print("east")
        }
    }

    enum Direction {
        case north
        case south
        case east
        case west
    }
    
    enum Directions {
    case north,south,east,west
    }
}

关联值

1.有时候会将枚举的成员值跟其他类型的关联存储在一起

enum Score {
  case points(Int)
  case grade(Character)
}
var score = Score.points(96)
score = .grade("A")

截屏2021-10-21 下午1.57.26.png

原始值

截屏2021-10-21 下午2.04.25.png

隐式原始值

截屏2021-10-21 下午2.06.53.png

递归枚举

截屏2021-10-21 下午2.11.49.png
使用递归枚举的时候，需要加入关键字indirect

MemoryLayout

用于查询内存占用

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        let pwd = Passwor.number(5, 6, 7, 8)
        print(MemoryLayout.size(ofValue: pwd)); // 33
        print(MemoryLayout.stride(ofValue: pwd));// 40
        print(MemoryLayout.alignment(ofValue: pwd));// 8
    }
    enum Passwor {
        case number(Int, Int, Int, Int)
        case other
    }
}
.size 是指实际占用大小
.stride 是指系统分配时给了多大
.alignment 是指按多大来对齐