Is there a reason a UIViewControllerRepresentable should never be a class? - swiftui

Question

Let's say that you don't really need SwiftUI features. I.e. you don't have import SwiftUI in your file. Instead, you only require
import protocol SwiftUI.UIViewControllerRepresentable
In general, you're going to have to involve a delegate object: an AnyObject at best, and usually, because the UIKit APIs are old, an NSObject.
The common pattern is to use a Coordinator class for that, and have the View itself be a struct, but is there always point in that indirection?
Here's an example which hasn't given me any trouble in practice:
import Combine
import MultipeerConnectivity
import protocol SwiftUI.UIViewControllerRepresentable
extension MCBrowserViewController {
final class View: NSObject {
init(
serviceType: String,
session: MCSession,
peerCountRange: ClosedRange<Int>? = nil
) {
self.serviceType = serviceType
self.session = session
self.peerCountRange = peerCountRange
}
private let serviceType: String
private unowned let session: MCSession
private let peerCountRange: ClosedRange<Int>?
private let didFinishSubject = CompletionSubject()
private let wasCancelledSubject = CompletionSubject()
}
}
// MARK: - internal
extension MCBrowserViewController.View {
var didFinishPublisher: AnyPublisher<Void, Never> { didFinishSubject.eraseToAnyPublisher() }
var wasCancelledPublisher: AnyPublisher<Void, Never> { wasCancelledSubject.eraseToAnyPublisher() }
}
// MARK: - private
private extension MCBrowserViewController {
typealias CompletionSubject = PassthroughSubject<Void, Never>
}
// MARK: - UIViewControllerRepresentable
extension MCBrowserViewController.View: UIViewControllerRepresentable {
func makeUIViewController(context: Context) -> MCBrowserViewController {
let browser = MCBrowserViewController(
serviceType: serviceType,
session: session
)
browser.delegate = self
if let peerCountRange = peerCountRange {
browser.minimumNumberOfPeers = peerCountRange.lowerBound
browser.maximumNumberOfPeers = peerCountRange.upperBound
}
return browser
}
func updateUIViewController(_: MCBrowserViewController, context _: Context) { }
}
// MARK: - MCBrowserViewControllerDelegate
extension MCBrowserViewController.View: MCBrowserViewControllerDelegate {
func browserViewControllerDidFinish(_: MCBrowserViewController) {
didFinishSubject.send()
}
func browserViewControllerWasCancelled(_: MCBrowserViewController) {
wasCancelledSubject.send()
}
}

Answer 1

I don't have a full detailed answer for your question, but your solution have some problems.
In SwiftUI, if we update a View, it calls init to recreate the View, and then call updateUIViewController.
In your case, whenever you update your View, not only your view is recreated, your two subjects will be recreated too, so anything attaches to the Publisher after the recreation won't receive events any more.
maybe that's the reason we prefer to use Coordinator.