Astronomer
An app that lets you search for Github users and look at who has starred their repositories.
This app was created as an architectural demonstration for my talk at the CocoaHeads Conference 2016.
Architectural overview
I didn't use a specific design pattern to build the app, there are elements from many different patterns, so I chose not to name any ;)
AppRouter
The router handles presentation of view controllers and navigation between them. The app's view controllers have delegate protocols the router implements to handle events that should trigger a navigation.
View Controller
Each view controller is responsible for configuring its views and implementing any view-specific protocols (data source, delegate, etc).
View Models
View models wrap the models and expose useful information that can be used by views and view controllers to present the model's information on screen. They are also responsible for implementing diffing between models.
Models
The models in this app are simple structs, they don't "do" anything, they only store data and implement the Equatable protocol.
Adapters
An adapter is an object that takes an input and transforms (adapts) it to a specific output. In this app there are adapters to take the json returned form the Github API and turn it into models.
Storage Controller
The storage controller takes models and stores them in a database (I'm using Realm).
API Client
The API client calls the Github API, gets the json data and turns it into model structs using adapters.
Data Provider
The data provider is the glue between the API Client, the Storage Controller and other objects that use the data (mainly view controllers).
The view controllers in this app don't talk to the network, they subscribe to obervers on the Data Provider, which uses the API Client to fetch data and stores the data on the database. By storing the data, it makes the observer emit a new event containing the updated results.
Both the API Client and Storage Controller implement protocols (APIClient and Storage), the Data Provider is injected with objects implementing these protocols, so both the API and storage layers can be changed without affecting the entire app (this is also useful when testing).
Testing
For this demonstration, I am only testing the adapters and the storage controller.
Dependencies
These are the dependencies I'm using:
- SwiftyJSON to parse JSON
- Siesta for networking
- Realm for data storage
- RxSwift for reactive extensions
- IGListDiff to do diffing between collections
Building steps
! Building tested on Xcode 8.1, macOS 10.12.1.
Clone the repository
$ git clone --recursive https://github.com/insidegui/Astronomer
Build dependencies
This project uses Carthage to manage its dependencies.
$ cd Astronomer/Astronomer && carthage update --no-use-binaries
Add Github API credentials
You will need a read-only personal access token from Github.
Rename the file Credentials_Sample.swift to Credentials.swift and enter your username and access token.