This assignment consists of a single screen where a user can search movies by typing keywords. It has been written in swift 4 for iPhone devices with minimum support for iOS 9. The user interface of the app is designed in auto layout.
This app additionally depends on following open source libraries.
- SDWebImage - For async image loading and caching
- UIScrollView-InfiniteScroll - For pagination support
The architecture of the app is MVVM (Model-View-ViewModel) with two additional layers for networking and persistence.
The models are implemented as data only structs. The models defining API responses implement Decodable protocol for mapping response data to swift structs.
The view controllers and storyboards are considered parts of this layer. The responsibility of this layer is only the presentation of data to user and receiving events from user.
The view models contain business logic of a view. Preparing data for presentation and handling user events are responsibilities of this layer.
A view model knows nothing about a view but emits events which a view observes to present data accordingly. The event listening is done in a single block providing event enum value. The primary reason for using a single callback is to reduce the possibility of infamous retain cycles.
This layer is responsible for executing web requests and providing response in asynchronous way. There is a APIClient protocol which expects the execution of a request. Its implementation is built on URLSession, but can be easily changed to any other networking library. The APIOperation protocol represents an executable api operation. So there would be a separate struct for each api endpoint.
This layer is responsible for persisting data based on repository pattern. So there would be a separate repository class for each different kind of entity.