众所周知,我们可以使用for..in循环遍历Arrays或Dictionaries。但是,我想这样迭代自己CustomClass:
for..in
Arrays
Dictionaries
CustomClass
for i in CustomClass { someFunction(i) }
CustomClass为了使之成为可能,必须支持哪些操作/协议?
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