添加“ for in”支持以遍历Swift定制类

假设您有一个类“ Cars”，希望使用for..in循环进行迭代：

let cars = Cars()for car in cars {    println(car.name)}

最简单的方法是将AnyGenerator与以下类一起使用：

class Car {    var name : String    init(name : String) {        self.name = name    }}class Cars : SequenceType {    var carList : [Car] = []    func generate() -> AnyGenerator<Car> {        // keep the index of the next car in the iteration        var nextIndex = carList.count-1        // Construct a AnyGenerator<Car> instance, passing a closure that returns the next car in the iteration        return anyGenerator { if (nextIndex < 0) {     return nil } return self.carList[nextIndex--]        }    }}

要尝试一个完整的工作示例，请添加上面的两个类，然后尝试像这样使用它们，并添加几个测试项：

    let cars = Cars()    cars.carList.append(Car(name: "Honda"))    cars.carList.append(Car(name: "Toyota"))    for car in cars {        println(car.name)    }

就是这样，很简单。

更多信息：http：//lillylabs.no/2014/09/30/make-iterable-swift-collection-
type-sequencetype