Combine class to manage cancellable instances instead of using a Set.

cancelbag.md

CancelBag

Adapted from https://gist.github.com/filimo/6f826b352f75cd1640e4e705340c0301

Instead of using a Set, use a CancelBag instead (kind of like the DisposeBag in RxSwift).

No need to use references when storing cancellables and you can also collect multiple cancellable instances without calling .store(in:).

Collecting

Before:

let subscriptions = Set<AnyCancellable>()

optionalPublisher?
    .sink { value in
        print("received value: \(value)")
    }
    .store(in: &subscriptions)
publisher
    .assign(to: \.someVar, on: self)
    .store(in: &subscriptions)
subject
    .subscribe(publisher2)
    .store(in: &subscriptions)

Now:

let cancelBag = CancelBag()

optionalPublisher?
    .sink { value in
        print("received value: \(value)")
    }
    .store(in: cancelBag)
publisher
    .assign(to: \.someVar, on: self)
    .store(in: cancelBag)
subject
    .subscribe(publisher2)
    .store(in: cancelBag)

Or even better:

let cancelBag = CancelBag()

cancelBag.collect {
    optionalPublisher?
    .sink { value in
        print("received value: \(value)")
    }
    publisher
        .assign(to: \.someVar, on: self)
    subject
        .subscribe(publisher2)
}

Canceling

It's as simple as:

cancelBag.cancel()

CancelBag.swift

import Combine
import SwiftUI

final class CancelBag {
    
    // MARK: - Properties

    var subscriptions = Set<AnyCancellable>()
    
    // MARK: - Actions
    
    /// Cancels and removes all cancellable instances stored within this `CancelBag`.
    func cancel() {
        subscriptions.forEach { $0.cancel() }
        subscriptions.removeAll()
    }
    
    /// Collects the cancellable instances provided by the given block.
    /// - Parameter cancellables:Block returning an array of cancellable instances.
    func collect(@Builder _ cancellables: () -> [AnyCancellable?]) {
        subscriptions.formUnion(cancellables().compactMap { $0 })
    }
    
    // MARK: - Builder
    
    @_functionBuilder
    struct Builder {
        static func buildBlock(_ cancellables: AnyCancellable?...) -> [AnyCancellable?] {
            cancellables
        }
    }
}

// MARK: - AnyCancellable

extension AnyCancellable {
    
    /// Stores this cancellable instance in the specified `CancelBag`.
    /// - Parameter cancelBag: `CancelBag` to store the cancellable instance.
    func store(in cancelBag: CancelBag) {
        cancelBag.subscriptions.insert(self)
    }
}