How to modify Object in Dependency Injection Pattern - ios

Question

So for the time I worked on the project and avoided Singletons and used Dependency Injection. By this I mean instead of creating a shared instance I created a class instance and passed to all controllers whichever needs.
Now my question, my model object which has references in all controllers, I need to point them either to a new object as for the requirements the data is fully updated like calling the init() again.
But if I do that in a certain controller that reference will only point to this new object.
So if you get what I mean I want the pointee of the references or where at memory address that object is there should be replaced to a new one and all references should still point to that old address / new object.

Answer 1

I think you need to inject not model in controllers, but service for obtaining and saving this model, something like this.
Protocol for service:
protocol ModelServiceProtocol {
func obtainModel(completion: (Model) -> Void)
func save(model: Model, compleiton: ()->Void)
}
Example ViewController with dependency:
class ViewController: UIViewController {
let modelService: ModelServiceProtocol
init(modelService: ModelServiceProtocol) {
self.modelService = modelService
}
func obtainModel() {
modelService.obtainModel { model in
// do something
}
}
func saveEditedModel() {
modelService.save(model: model) {
// model saved
}
}
}
Implementation of ModelService that will obtain and save your model:
class ModelService: ModelServiceProtocol {
func obtainModel(completion: (Model) -> Void) {
// implementation of obtainig model from some storage
}
func save(model: Model, compleiton: ()->Void) {
// implementation of saving model in some storage
}
}
Injection of dependency:
func buildController() -> ViewController {
let modelService = ModelService()
let viewController = ViewController(modelService: modelService)
return viewController
}
In this approach you will get actual model in ViewController, edit and save to some storage. Model will be actual on every step