Code exercises for iOS candidates

To complete this exercise successfully, you need to do the following:

1. Clone the ios-exercises repo to your computer.
2. Fix any runtime errors and console warnings.
3. Consume the following endpoint and deserialize the JSON response: https://www.weightwatchers.com/assets/cmx/us/messages/collections.json
4. With the data from this endpoint, display the title and image of each object in the response. You can use any UIView or UIControl to do this.
5. Run the application in the Simulator or on an iOS device.
6. Ensure the app displays correctly when the orientation changes.
7. Submit your completed updates to the ios-exercises repo using a pull request.

Bonus Points

• Replace PureLayout with a solution that supports Safe Area Layout Guide for iPhone X
• Display a placeholder image if the URL is invalid
• Display an alert when the image is tapped

To complete this exercise, you need to do the following:

• Clone the ios-exercises repo, if you haven't already.
• Open Exercise2.playground in Xcode.
• Fix compilation errors.
• Assign the teacher the name "Alice" and an age of 31.
• Implement addStudents() to add Cecilia, Ellen, and Bob to Alice's list of students.
• In printStudents(), print the student's age if it's available. Otherwise, just print the name.
• Submit your completed updates to the ios-exercises repo using a pull request.

TBD

To eliminate Singleton Pattern, protocols are used to "hide" singleton instances and indicate dependencies. For example, even though cuisine data are stored in a shared instance of CuisineManager, view model that requires these data need to confirm to protocol RequiresCuisineData to access the shared cuisineManager instance. This is to prevent global level dependency: nothing should be required by everything.

Also, protocols are widely used as interfaces. In theory all non UI modules should provides protocols to make unit tests easier, and even UI related modules can work in this way to support multiple implementation. Currently only one dummy implementation DummyViewModel is provided.

DependencyManager, which is based on Dip, handles runtime dependency injection. Even DependencyManager can be replaced by other implementations like Swinject easily, as long as it's renamed to DipDependencyManager and a protocol DependencyManager is created. As mentioned in About Protocols, even though the manager itself is a shared singleton instance, it should only be accessed by classes that confirm to protocol RequiresDependency.

Architecture design of this app is inspired by Android Architecture Components. The general idea is that UI elements in ViewControllers are bind with MutableProperties in ViewModels (like LiveData in Google's library). In another word, ViewControllers passively observe changes of ViewModels in a reactive way, and the actual business logic is handled in ViewModels. ViewModels do not depend on UIKit at all, which makes them easier to test.

To get data, ViewModels talk with Managers, which may be called repositories, data source, or data store as well. Please note that there are also UI Managers like CuisineTableManager, which are different since UI Managers are related with UIKit components, e.g. UITableViewDataSource. UI Managers only handles UI logic in a passive way, and they generate different Views like CuisineTableCell, which talks with CuisineCellViewModel and again, CuisineCellViewModel handles business logic.

NavigationManager is part of UI. It handles lifecycle of the whole app, and is called by UI sub-modules. In this example, there is no navigation at all so it only provides minimium functionality.

Models (or Entities) are implemented based on EVReflection, ReflectionNetworkManager utilizes it and results less code, but can be slow deserializing complex data structure. MoyaNetworkManager runs much faster, and you can always swap dependencies in DependencyManager to see the difference.

• WWDependencyTests: ensure dependency manager is setup correctly.
• WWNetworkTests: async test.
• WWNetworkReflectionTests: how to switch dependency at run time.

More unit tests / UI tests should be added, but I'm too sick to do so - 06/30/2018