This project uses Unsplash API to get images, you can save favorite images and see details
Go to the root of your project and look for local.properties (it should be in your git.ignore), then you should add something like:
UNSPLASH_TOKEN=<TOKEN YOU GET FROM UNSPLASH>
To get a token you should register here and create an application.
This is the typical master-detail app over a list of images provided by Unsplash API. Additionally, you can choose favorites (locally) and it will persist. The main purpose of this project is to try to be a playground of the new Jetpack Compose for declarative UIs.
All the screens are hosted by MainActivity.kt and you can navigate through Jetpack Navigation Compose among the three screens the app has which are:
- HomeScreen.kt you can find the complete list of images here. They are consumed from the Network and it has a cache policy to work without Internet, this was implemented using Paging 3 library (Using RemoteMediator), Room DataBase.
- FavoritesScreen.kt This is pretty similar to HomeScreen.kt, the difference is the source of data, which is Room which handles the persistency locally, additionally, you can find an implementation of a SearchBar to find specific images.
- DetailScreen.kt this is the most complex screen in terms of Jetpack Compose due to the number of composables it has, you can find an implementation of a sliding Toolbar, Shimmer loader, Box composable. Additionally, you can add favorites from there.
One interesting thing about this project is that just one ViewModel was created to handle all the screens. SharedViewModel.kt is shared and is the bridge of communication among the screens. It offers a StateFlow to get updates in case some favorite is modified. Apart from that, it is observing changes in the local database created with Room.
The orchestrator for navigation is UnsplashApp.kt you can find there the main structure of the application which is an Scaffold with a BottomNavigation. The BottomNavigation navigates either HomeScreen or FavoritesScreen and inside those screens, you can navigate to DetailScreen.
The navigation is managed by AnimatedNavHost which is similar to NavHost with the difference that you can create animations every time you navigate from one screen to another.
Hilt is the new tool to handle dependency injection in Android so it was used to do that. You can find three modules:
- CoreModule.kt provides the data bases (created in Room) to UnsplasRepository.kt
- NetworkModule.kt provides the REST client which is Retrofit 2 in this case. It also provides AuthInterceptor which sets the auth config to Retrofit.
- ViewModelsModule.kt this is scoped with ViewModelComponent and provides the dependencies to SharedViewModel.kt for this particular case.
- Every time you go to DetailScreen and you go back the scroll position is lost.
- Liskov principle is not implementing