download an image using combine in swift

To download an image using Combine, you need to use URLSession to make a network request and then decode the response into an image. Here's an example of how you can do it:

main.swift
import Combine
import UIKit

func downloadImage(from url: URL) -> AnyPublisher<UIImage?, Never> {
    URLSession.shared.dataTaskPublisher(for: url)
        .map { data, _ in UIImage(data: data) }
        .replaceError(with: nil)
        .eraseToAnyPublisher()
}

let imageURL = URL(string: "https://www.example.com/image.png")!
let imagePublisher = downloadImage(from: imageURL)
imagePublisher
    .sink(receiveValue: { image in
        // Do something with the downloaded image
    })
486 chars
17 lines

In this example, downloadImage(from:) takes a URL and returns a publisher that emits a UIImage or nil, and never fails. It uses dataTaskPublisher(for:) to create a publisher that emits a (data: Data, response: URLResponse) tuple when a network request completes. Then, it maps the data to a UIImage, replaces any errors with nil, and erases the types to create a publisher that emits a UIImage?.

To use downloadImage(from:), you call it with a URL, which returns a publisher that you can subscribe to, typically using sink(receiveValue:). In the closure, you can do something with the downloaded image, like displaying it in an image view.