Joao is available for hire

Joao Vital

Verified Expert in Engineering

iOS Developer

Salvador - State of Bahia, Brazil

Toptal member since August 24, 2017

Expertise

Java iOS Objective-C Swift Linux Xcode Agile Development MySQL Git SQL C

Bio

Joao is a seasoned software engineer with a passion for user experience. He began his journey as a Java developer, but eventually, he transitioned to iOS development because it allowed him to put his focus on user experience at the forefront. With a keen interest in software architecture and good instincts to avoid overly complex solutions, Joao thrives in team environments making him a valuable asset to any project.

Portfolio

Netspend

iOS, Swift, RxSwift

Duolingo, Inc.

iOS, Swift, Objective-C, Cocoa Touch, SwiftUI, API Integration...

Freelance Clients

Sketch, GPUImage, Objective-C, iOS, Swift, User Experience (UX), Swift 4, Xcode...

Experience

Software Design - 14 years
Java - 14 years
User Experience (UX) - 10 years
iOS - 10 years
Swift - 5 years
Objective-C - 5 years
Model View ViewModel (MVVM) - 4 years
Model View Presenter (MVP) - 4 years

Availability

Full-time

Preferred Environment

Linux, MacOS, Eclipse, Xcode

The most amazing...

...piece of software I've created is a framework of components for building Java apps using the Observer pattern and many new ideas at the time.

Work Experience

Senior iOS Developer

2024 - 2025

Netspend

Worked at Netspend, a fintech company focused on debit cards. Joined the team working on rebuilding the app from scratch using Swift 5.
Used the Uber RIBs architecture with RxSwift 6.7, enabling reactive programming to bind the business layer with the UI efficiently. This architecture allowed us to work in small, independent code units, facilitating effective unit testing.
Used Mockolo to generate mocks and a custom fixtures framework to create network models for quick testing.
Used the SnapKit framework to build the UI with view code.
Worked on building the Rewards feature of the wallet app.

Technologies: iOS, Swift, RxSwift

iOS Engineer (via Toptal)

2023 - 2024

Duolingo, Inc.

Worked as part of the Delight team and enhanced the app's UI and UX, building new features with great attention to detail.
Created new components to be used in several different parts of the app.
Created animations with custom animation curves and haptic feedback using advanced UIKit and Core Haptics.
Refactored legacy code and replaced old components with new ones as experiments.
Implemented integration in the app with reCAPTCHA Enterprise 18.1.

Technologies: iOS, Swift, Objective-C, Cocoa Touch, SwiftUI, API Integration, User Interface (UI)

Software Developer

2012 - 2022

Freelance Clients

Developed a portfolio of iOS multimedia and entertainment apps using Swift and Objective-C. Leveraged advanced libraries like AVFoundation, GPUImage, the Hero transition library, and Core Image to bring ideas to life.
Learned what it takes to build exceptional mobile user experiences and developed a keen eye for design, using tools such as Sketch and Figma.
Improved my knowledge about marketing apps through marketing networks.

Technologies: Sketch, GPUImage, Objective-C, iOS, Swift, User Experience (UX), Swift 4, Xcode, Cocoa Touch, API Integration, User Interface (UI)

Software Developer

2007 - 2021

Serpro

Worked on the first mobile apps created for the Brazilian IRS. Faced challenges such as defining the initial project architecture, integrating different platforms and codebases, and refactoring legacy code while mentoring a team of four developers.
Used the observer pattern and automatic data binding to build a framework of reusable components that made developing apps faster and easier and wrote a paper about it.
Contributed to the development of multiple government solutions, including the tax declaration software used by 30 million taxpayers.
Mentored teams in different parts of the country, attending to their project's demands and helping them figure out the best way to handle them.
Developed a solution for replacing JavaHelp with PDF files integrated with the app while keeping changes to the original codebase at a minimum. This new solution positively impacted the project's budget and productivity.
Wrote unit tests and integration tests in Swift and Java.
Built a custom-made solution that provides auto-update for Java Desktop apps.
Maintained an internal website with best practices for my team's projects.
Installed and customized TWiki to be used as a documentation tool at the company.

Technologies: TestFlight, Ant Design, Apache Maven, Git, Swing, Java, Objective-C, iOS, Desktop App Development, Software Design, Leadership, Model View ViewModel (MVVM), Model View Presenter (MVP), Alamofire, Core Data, J2ObjC, XCTest, User Experience (UX), Swift 4, Xcode, Cocoa Touch, SQLite, API Integration, User Interface (UI)

Open-source Developer

2005 - 2007

Freelance

Contributed with code to the GNU Classpath project.
Contributed to the Java-Gnome project and wrote documentation for it.
Managed the improvement of the Java-Gnome website and developed a Linux distro based on Knoppix.
Presented at Free Software events about the Java-Gnome and Autopackage projects.

Technologies: GNOME, GTK+, Java, Linux, GTK

Experience

IRPF Application

Worked on the IRS Tax Declaration app for the Brazilian government, used by 30 million people. I was the developer responsible for implementing the project's initial architecture and subsequent improvements. Throughout this project, I faced exciting challenges, such as handling different codebases and platforms, like iOS, Android, Web, and Desktop. Additionally, I mentored a small team of developers, helping them grow and succeed.

Tinge | Retro Filters

https://apps.apple.com/us/app/tinge-duotones/id561464798

Tinge is an app for filtering photos and videos with color. The entire app and all its filters were created by myself, inspired by old-school design and fashion aesthetics.

Apple has listed Tinge as an artistic app inside the App Store's photo and video page.

Soundgramr

https://soundgramr.wordpress.com

Soundgramr was an exciting idea I tried to develop. It was a camera app that recorded the environment's sounds as users snapped pictures. Later, users could listen to the images and tell a story through these "soundgrams."

The app ended up being the object of study for a doctoral thesis titled Escuta, Gravação, Plataforma Web: Fazer Mapa Sonoro Como Conjunto de Práticas de Mídia, Aragão, 2018, UNISINOS.

More about the app: https://www.apppicker.com/reviews/4408/Soundgramr-app-review

Reverse Music Player

A fully featured backward player. Record or play songs from the music library backward to find hidden messages or just have fun. I implemented the backward functionality from scratch by manipulating the song file with AVFoundation.

Sweet Photo Booth

A photo booth app for iPhone. I created a fun and playful camera application with a joyful aesthetic to be used with friends. I built the app from the ground up, focusing on design and user experience.

Rearrange | Photo Collage

https://tingeapp.com/other-apps-rearrange/

Rearrange was built upon iOS aesthetics to deliver a unique idea: a collage app with only one screen. Rearrange lets users intuitively create and modify photo collages using gestures and motion effects.

When I started developing Rearrange, there was no such app as Layouts for making photo collages, so this was an exciting new idea at the time.

Education

2000 - 2004

Bachelor's Degree in Computer Science

Universidade Salvador (UNIFACS) - Salvador, State of Bahia, Brazil

Skills

Libraries/APIs

GPUImage, Proguard, JasperReports, Firebase iOS SDK, Flurry, REST APIs, Core Image, Alamofire, RxSwift

Tools

Xcode, Eclipse IDE, GTK+, GNOME, Apache Maven, Git, HSQLDB, Postman, Apache Ant, Sketch, TestFlight, J2ObjC, GTK

Languages

Objective-C, Java, Swift, Swift 4, SQL, C

Frameworks

Swing, Cocoa Touch, UIKit, SwiftUI, Ant Design, Core Data, XCTest, MapKit

Platforms

iOS, Linux, Eclipse, MacOS, Firebase

Paradigms

Desktop App Development, Model View ViewModel (MVVM), Model View Presenter (MVP), Agile Software Development

Storage

Microsoft SQL Server, MySQL, SQLite

Other

User Experience (UX), User Interface (UI), Usability, Software Design, Architecture, API Integration, AVFoundation, Component Libraries, iPad, Leadership, Shell Scripting, Computer Science

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