还记得字典吗？
- var numberOfLegs= ["spider": 8,"ant": 6, "cat":4]
- numberOfLegs["bird"]= 2
["bird"]就是下标 下标可以在类和结构体中定义。
定义下标
- subscript(index: Int) -> Int {
- get {
- //return anappropriate subscript value here
- }
- set(newValue) {
- // perform a suitable settingaction here
- }
- }
只读下标
- subscript(index: Int) -> Int {
- //return anappropriate subscript value here
- }
实例：
- struct TimesTable {
- let multiplier: Int
- subscript(index: Int) ->Int {
- return multiplier * index
- }
- }
- let threeTimesTable = TimesTable(multiplier: 3)
- println("sixtimes three is \(threeTimesTable[6])")
- // prints"six times three is 18"
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