Combine Publishers Zip

PublishersCombine.swift

//
//  ViewController.swift
//  CombineCombine
//
//  Created by Woody Liu on 2021/8/16.
//

import UIKit
import Combine

class ViewController: UIViewController {
    
    var anyCancellables = Set<AnyCancellable>()
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
   
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        mergeMany()
    
        zipSuccess()

        zipFail()

        zipInZip()
        
        
    }
    
}


extension ViewController {
    
    fileprivate func mergeMany() {
        // MARK: MergeMany 處理不同型別
        Publishers.MergeMany(Task.fetchInt(int: 5), Task.fetchString(string: "ABC"), Task.fetchPotin(point: .init(x: 0, y: 1)))
            .eraseToAnyPublisher()
            .collect(3)
            .sink { arr in
                print(arr)
                arr.forEach {
                    if let int = $0 as? Int {
                        print(int)
                    }

                    if let string = $0 as? String {
                        print(string)
                    }

                    if let point = $0 as? CGPoint {
                        print(point)
                    }

                }
            }.store(in: &anyCancellables)
    }
    
    fileprivate func zipSuccess() {
        // MARK: zIP 3 成功
        Publishers.Zip3(Task.fetchInt(int: 10), Task.fetchString(string: "BCD"), Task.fetchPotin(point: .init(x: 1, y: 1)))
            .tryMap { value -> (Int, String, CGPoint) in
                if let int = value.0 as? Int,
                   let string = value.1 as? String,
                   let point = value.2 as? CGPoint {
                    return (int, string, point)
                }else {
                    throw CombinError.convertFail
                }
            }.sink(receiveCompletion: {
                switch $0 {
                case .failure(let error):
                    print(error)
                default:
                    break
                }
            }, receiveValue: {
                print($0)
            }).store(in: &anyCancellables)
    }
    
    fileprivate func zipFail() {
        // MARK Zip3 失敗版
        Publishers.Zip3(Task.fetchInt(int: 11), Task.fetchString(string: "BCDF"), Task.fetchPotin(point: .init(x: 1, y: 5)))
            .tryMap { value -> (Int, String, CGFloat) in
                if let int = value.0 as? Int,
                   let string = value.1 as? String,
                   let point = value.2 as? CGFloat {
                    return (int, string, point)
                }else {
                    throw CombinError.convertFail
                }
            }.sink(receiveCompletion: {
                switch $0 {
                case .failure(let error):
                    print(error)
                default:
                    break
                }
            }, receiveValue: {
                print($0)
            }).store(in: &anyCancellables)
    }
    
    fileprivate func zipInZip() {
        // MARK: 巢狀Zip
        Publishers.Zip(createZip(), createZip())
            .tryMap { tuple-> [(Int, String, CGPoint)] in
                var arr = Array<(Int, String, CGPoint)>()

                if let value = tuple.0 as? (Int, String, CGPoint) {
                    arr.append(value)
                }

                if let value = tuple.1 as? (Int, String, CGPoint) {
                    arr.append(value)
                }
                return arr
            }.sink(receiveCompletion: {
                switch $0 {
                case .failure(let error):
                    print(error)
                default:
                    break
                }
            }, receiveValue: {
                print($0)
            })
            .store(in: &anyCancellables)
    }
//
    private func createZip()-> AnyPublisher<Any, CombinError> {
        return Publishers.Zip3(Task.fetchInt(int: 11), Task.fetchString(string: "BCDF"), Task.fetchPotin(point: .init(x: 1, y: 5)))
            .tryMap { value -> (Int, String, CGPoint) in
                if let int = value.0 as? Int,
                   let string = value.1 as? String,
                   let point = value.2 as? CGPoint {
                    return (int, string, point)
                }else {
                    throw CombinError.convertFail
                }
            }
            .mapError( { if let error = $0 as? CombinError {
                return error
            }
            return CombinError.convertFail
            })
            .eraseToAnyPublisher()
    }
}

enum CombinError: Error {
    case convertFail
}


class Task {
    
    static let int = PassthroughSubject<Any, Never>()
    static let string = PassthroughSubject<Any, Never>()
    static let point = PassthroughSubject<Any, Never>()
    
    static func fetchInt(int: Int)-> Future<Any, Never> {
//    static func fetchInt(int: Int)-> PassthroughSubject<Any, Never> {
        return Future<Any, Never> { promise in
            DispatchQueue.global().asyncAfter(deadline: .now() + 1) {
                print("Int is promise", Date())
                promise(.success(int))
//                Task.int.send(int)
            }
            DispatchQueue.global().asyncAfter(deadline: .now() + 7) {
                print("Int is promise", Date())
                promise(.success(int))
//                Task.int.send(int + 1)
            }
        }
        
//        return Task.int
    }
    
    static func fetchString(string: String)-> Future<Any, Never> {
//        static func fetchString(string: String)-> PassthroughSubject<Any, Never> {

        return Future<Any, Never> { promise in
            DispatchQueue.global().asyncAfter(deadline: .now() + 4) {
                print("string is promise", Date())
                promise(.success(string))
//                Task.string.send(string)
            }
            DispatchQueue.global().asyncAfter(deadline: .now() + 9) {
                print("string is promise", Date())
                promise(.success(string))
//                Task.string.send(string + "delay")

            }
        }
//            return Task.string
    }
    
    static func fetchPotin(point: CGPoint)-> Future<Any, Never> {
//        static func fetchPotin(point: CGPoint)-> PassthroughSubject<Any, Never> {

        return Future<Any, Never> { promise in
            DispatchQueue.global().asyncAfter(deadline: .now() + 6) {
                print("point is promise", Date())
                promise(.success(point))
                Task.point.send(point)
            }
            
            DispatchQueue.global().asyncAfter(deadline: .now() + 10) {
                print("point is promise", Date())
                promise(.success(point))
                var point = point
                point.y = 9
//                Task.point.send(point)
            }
        }
//            return Task.point
    }
    
}