eraseToAnyPublisher()
方法将复杂的 Publisher 转化为对应的通用类型AnyPublisher
。import Combine
// p1类型: Publishers.FlatMap<Publishers.Sequence<[Int], Never>, Publishers.Sequence<[[Int]], Never>>
let p1 = [[1, 2, 3], [4, 5, 6]]
.publisher
.flatMap { $0.publisher }
// p2类型: Publishers.Map<Publishers.FlatMap<Publishers.Sequence<[Int], Never>, Publishers.Sequence<[[Int]], Never>>, Int>
let p2 = p1.map { $0 * 2 }
// p3类型: AnyPublisher<Int, Never>
let p3 = p2.eraseToAnyPublisher()
eraseToAnyPublisher
进行类型抹消后的 Publisher 变得简单明了易于理解,这在实际开发中经常使用。import UIKit
import Combine
class DataPublisher {
private var dataPublisher: AnyPublisher<URLSession.DataTaskPublisher.Output, URLSession.DataTaskPublisher.Failure>
var cancellable: AnyCancellable?
init(){
let url = URL(string: "http://v.juhe.cn/toutiao/index?type=top")
let request = URLRequest(url: url!)
let session = URLSession.shared
// 1. 创建发布者
self.dataPublisher = session.dataTaskPublisher(for: request).eraseToAnyPublisher()
// 2. 订阅
cancellable = dataPublisher
.receive(on: DispatchQueue.main).sink(receiveCompletion: {_ in
}) { (data: Data, response: URLResponse) in
}
}
}
eraseToAnySubscriber
和eraseToAnySubject
。