Swift 学习笔记 「集合类型」

#Program

###数组

  • 声明

      var shoppingList: String[] = ["Eggs", "Milk"]
    

    但由于 Swift 的类型推导,你这么写也是可以的。

      var shoppingList = ["Eggs", "Milk"]
    
  • 方法

    确定数组内元素的个数

      shoppingList.count
    

    在数组最后添加一个元素

      shoppingList.append("Flour")
    

    也可以

      shoppingList += "Baking Powder"
    

    替换元素,Swift 允许替换范围大于替换后的元素个数

      shoppingList[4...6] = ["Bananas", "Apples"]
    

    在具体某个位置添加元素

      shoppingList.insert("Maple Syrup", atIndex: 0)
    

    移除具体某个位置的元素

      let mapleSyrup = shoppingList.removeAtIndex(0)
    

    获取数组下标和对应的值

      for (index, value) in enumerate(shoppingList){...}
    

###字典

  • 声明

      var airports: Dictionary<string, string> = ["TYO":"Tokyo", "DUB":"Dublin"]
    	
      var namesOfIntegers = Dictionary<Int, String>()
    
  • 方法

    统计字典元素个数

      airports.count
    

    更新字典值,如果不存在该 key ,则会返回 nil

      let oldValue = airports.updateValue("Dublin International", forKey: "DUB")
    

    删除字典值

      let removedValue = airports.removeValueForKey("DUB")
    

    获取字典 key

      let airportCodes = Array(airports.keys)
      for airportCode in airports.keys{...}
    

    获取字典 value

      let airportName = Array(airports.values)
      for airportName in airports.values{...}