Coordinator Pattern

Thanks to Paul Hudson

Problem:

UIViewController: is it view or is it controller ? The MVC pattern relies on stuffing the viewController with much functionalities it may contain:

1- Inserts new model objects 2- NSFetchedResultsControllerDelegate 3- Handles Navigation 4- TableView Delegates 4- datasources ....

Coordinator pattern helps in:

1- Control the flow of the app 2- Handle iPhone/iPad variants 3- Handle A\B testing variants

Steps to create coordinators

1- create a coordinator protocol

• contain a child of coordinators
• navigation controller instance
• start method ... start()

2- add a concrete implementation of that protocol 3- connect the viewController to the coordinator, ViewController shall no more be responsible for creating other viewControllers and presenting it, remove tight coupling.

1- how and when use child coordinators avoid massive coordinators

2- navigate backword what happens if U have multiple viewControllers being shown in the child Coordinator (some other view presented modally) ... viewDidDispear will be called prematurely

3- passing data between coordinators Key is one ViewController does not know that other exisit, passing data to the coordinator then can go any where(triger a network request or open another view), the coordinator figures out the destination it decide what the values should mean