StatefulVC

Info

This is a simple MVVM-based reactive-whatever architecture bundle for iOS built upon UIKit and Combine.

Import

You can import this as a SPM package in Xcode:

https://github.com/nekonora/StatefulVC.git

Example

Let's say we have a scene that needs to display a collection of books from an author. These books could be as well retrieved from an external service.

Every view model has config and data properties of the type defined by its class's generics. data is self-explanatory: it's the data the scene is going to manage/display. config is any other possible data type that could be used to configure the scene.

We create subclasses of StatefulVC and StatefulVM, specifying the types of config and data:

class BooklistVM: StatefulVM<Config, [Book]> { ... }

class BooklistVC: StatefulVC<Config, [Book], BooklistVM> { ... }

We then create an instance of the scene like this:

let booklistVC = BoolistVC.instance(with: BooklistVM(config: config, data: author.books))

or (if you like to use storyboards):

let booklistVC = BoolistVC.storyboardInstance(with: BooklistVM(config: config, data: author.books))

In our view model, we can override the bindSubscriptions() method to provide our implementation of how the view controller's view should be updated. For example, let's say that some service or method updates the array of books stored in data: we can update the view accordingly by calling updateViewState():

/// In BooklistVM

override func bindSubscriptions() {
    $data
        .dropFirst()
        .sink { self.updateViewState(.data($0)) }
        .store(in: &subscriptions)
}

We then decide what the view should do when the data state is set:

/// In BooklistVC

override func onStateData(data: [Book]) {
    applyDataSnapshot(data)
}

Done!

You can look at the tests for an example of how this is intended to work.