Photo Viewer

A photo viewer application which consumes a third-party photos API. Basically the application has 3 features:

• List the newest photos uploaded to the API
• Search a photo by terms
• Show the photo's details which can be downloaded to your photo library.

There are some improviments that I would like to do if I have more time, which are:

• Dynamic UICollectionViewCell's height by photo (like Pinterest)
• More photo's info like related collections
• A section of favorite photos (maybe save in a local database)
• User session to interact more with the API for example like photos, upload new photos and follow people

The API that I've used to build these project is from https://unsplash.com and I've used requests that doesn't need to be authenticated. It does not provide optimized photos, so the app on debug can appear consuming more memory than others photo viewer apps.

In this project the iOS stack was:

• Swift 5.0
• Xcode 11.3
• VIPER architecture
• Coordinator pattern
• Factory pattern

Installation

To manage all dependencies the project is using Cocoapods.

To install cocoapods you need set your gemset on RVM, run these commands lines on your shell:

$ echo photo-viewer-ios > .ruby-gemset && echo 2.6.3 > .ruby-version
$ cd .

After install bundler to install all gem dependencies:

$ gem install bundler

Run bundler

$ bundle

After installing cocoapods run this command to install all project's dependencies:

$ pod install

And then open PhotoViewer.xcworkspace and now you can run the project.

Architecture concept

In VIPER it's normal to use Input and Output protocols to comunicate between VIPER modules, but with reactive programming we can simplify it by making one way binding. So every module only has the Input protocol that contains signals and actions that these modules can do.

So the flow is:

The project is using RxSwift and RxCocoa to implement this flow without Input/Output protocols.

Also I've implemented two Design Patterns to increase the maintainability of this project. These patterns are Coordinator and Factory.

Factory

It's using to create VIPER modules, and it's powerful to inject all VIPER dependencies.

Coordinator

It's using to manage all project navigation. It's in charge to implement Routing protocol from modules.

Instead of using WireFrames, the Coordinators bring more flexibility to use a module in differentes flows with diffrerents contexts and approaches and is clearer understand flows and features.

Outsource libraries

I've used a couple of outsource libriries to save time to develop the main feature, which are:

PhotoViewer target

• RxSwift brings flexibility to code;
• RxCocoa makes some cocoa components reactive to be easier integrate with RxSwift events;
• Moya/RxSwift is an easy network abstration layer to make request to an API and transforming into a Rx signal;
• Mextension my own library that contains a couple of extensions that I always use in my projects;
• INSPullToRefresh to create infinity scroll pagination;
• Kingfisher downlod and cache images.

Tests targets (Unit and UI)

• Quick a behavior-driven development framework to create tests inspired by RSpec
• Nimble a framework to express the expected outcomes tests and simplify the asserts
• RxTest a framework to test RxSwift events
• RxBlocking a framework to transform async RxSwift events in sync events, it's used to create tests and just for it
• RxNimble a Nimble extensions to create unit tests easier
• Swifter create a Http server to run mock requests

Author

Vitor Mesquita, vitor.mesquita09@gmail.com Brazil