TaskStore

A Store where you can temporarily hold the tasks that describes in Swift concurrency. It is useful when you want to cancel specific tasks at the appropriate points.

For example, it can be used to fetch the image for UITableViewCell using Task.
In this case, we require to cancel the Task, however, it's not that simple without other implementation changes.
The following shows example code how to resolve this problem by storing the tasks. Plus, it is a way that reaches out the goal with only additional code, no removed code.

Before

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(CustomCell.self, for: indexPath)
    Task {
        guard let response = await network.request(url: url) else { return }
        guard let imageURL = URL(string: response.imageURL) else { return }
        let image = await imageLoader.load(from: imageURL)
        cell.update(image: image)
    }
    return cell
}

After

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(CustomCell.self, for: indexPath)
    // ✨ For identifing tasks
    let cellID = ObjectIdentifier(cell)

    // ✨ Cancel tasks that no longer needs
    taskStore.tasks(where: { $0.cellID == cellID })
        .forEach { $0.cancel() }

    // ✨ Assign to variable
    let imageUpdateTask = Task {
        guard let response = await network.request(url: url) else { return }
        try Task.checkCancellation() // ✨ Check cancellation at the appropriate time.

        guard let imageURL = URL(string: response.imageURL) else { return }
        let image = await imageLoader.load(from: imageURL)
        try Task.checkCancellation() // ✨ Check cancellation at the appropriate time.

        cell.update(image: image)
    }
    // ✨ Store a task 
    taskStore.setTask(imageUpdateTask, forKey: CellImageUpdateKey(cellID: cellID, indexPath: indexPath))
    
    return cell
}

You can use it anywhere you want to store a Task, not just in the example above!

Features

• The stored tasks are automatically removed from the store when it completed.("Removed" means to removed from memory and can't access anymore)

How it works?

When you store the task, it creates a parent task that will deallocate the stored one. This parent task is waiting for the associated task(the stored task) completed or cancelled, and it has lowest priority so that executes in the background.

Contribution

Welcome any contributions via issue or pull request, such as any features you'd like to see added, bug reports, etc. 🙌

Installation

dependencies: [
    .package(url: "https://github.com/woin2ee/TaskStore.git", .upToNextMajor(from: "0.1.0"))
]