fetch all link from request

fetchAll.swift

import Foundation
import PlaygroundSupport
import Combine

PlaygroundPage.current.needsIndefiniteExecution = true

enum RequestError: Error {
    case sessionError(error: Error)
}

var cancellableSet: Set<AnyCancellable> = []
URLSession.shared.dataTaskPublisher(for: request)
    .tryMap { $0.data }
    .decode(type: APIStruct.self, decoder: JSONDecoder())
    .map{ $0.Data.map{$0.thumb} }
    .map{ links -> [AnyPublisher<(URL, String), Error>] in
        links.map{ link in
            URLSession.shared.dataTaskPublisher(for: link)
                .map{$0.response.mimeType ?? ""}
                .map{ (link, $0) }
                .mapError { error -> RequestError in
                    return RequestError.sessionError(error: error)
                }
                .eraseToAnyPublisher()
        }
    }.flatMap{ tasks -> Publishers.MergeMany<AnyPublisher<(URL, String), Error>> in
        Publishers.MergeMany(tasks)
    }.collect()
    .sink { result in
        print("api: \(result)")
        PlaygroundPage.current.finishExecution()
    } receiveValue: { values in
        var mimes = [String: Int]()
        values.forEach{ value in
            let link = value.0
            let mime = value.1
            print("\(link) is \(mime)")
            var count = mimes[mime] ?? 0
            count += 1
            mimes[mime] = count
        }
        print("total: \(values.count)")
        print(mimes)
    }.store(in: &cancellableSet)