责任链模式 Chain Of Responsibility

责任链模式是适用于流程样式过程，比如流水线，OA审批过程

优点：各司其职，便于扩展

缺点：每一次必须走流程，按照步骤走

我们使用责任链来解决一个货币找零问题——要求找零是张数最少

描述：将一定数量的金额兑换出张数最少的纸币（目前币种有 100，50 ，20，10， ， 1，， 0.1）

比如：102= 100 * 1 + 1*2   125 = 100 *1 …

分析：这个就是一个流程问题，先从最大币值开始，一直往下走，这样纸币的数量才会最少

先定义纸币的枚举类型

enum iConKind: Int {
    case Jiao = 1
    case Yuan = 10
    case Ten = 100
    case Twenty = 200
    case Fifty = 500
    case Hundred = 1000
}

然后定义纸币的实体lei

public class Money {
    private var realMoney: Float ?
    internal var total: Float ?{
        didSet {
         realMoney = self . total ! * 10
        }
    }
    public var nextMoney: Money ?
    var kind: iConKind
   
    init ( moneyKind: iConKind , nextOne: Money ?){
        self . kind = moneyKind
        self . nextMoney = nextOne
    }
    public func doExchange(){
   
        if let next = self . nextMoney {
            var nextTotal = self . realMoney ! % Float ( self . kind . rawValue )
            next. total = nextTotal / Float ( 10 )
            next. doExchange ()
            var number = Int ( self . realMoney !) / self . kind . rawValue
        println ( " 币种 \ ( self . kind . rawValue / 10 ) 个数 \ ( number )" )
        } else {
        println ( " 币种   \ ( self . kind . rawValue ) 角 个数 \ ( Int ( self . total !* 10 ) )" )
        }
    }

}

 

使用

var jiao = Money (moneyKind: . Jiao , nextOne: nil )
var yuan = Money (moneyKind: . Yuan , nextOne: jiao )
var ten = Money (moneyKind: . Ten , nextOne: yuan )
var twenty = Money (moneyKind: . Twenty , nextOne: ten )
var fifty = Money (moneyKind: . Fifty , nextOne: twenty )
var hundred = Money (moneyKind: . Hundred , nextOne: fifty )
hundred . total = 188.8

hundred . doExchange ()