Paulo is available for hire
Hire PauloPaulo Fierro
Verified Expert in Engineering
UIKit Developer
George Town, Cayman Islands
Toptal member since December 3, 2013
Bio
Paulo has been an app developer for iPhones since 2009. His passion is building apps for iOS and macOS that deliver lovely user experiences that make life a little bit easier. Paulo has built award-winning iOS apps that have been featured by Apple and reached the top of the App Store charts.
Portfolio
jadehopper
RxSwift, WatchOS, Mobile Prototypes, UI Design, Git, Agile Software Development...
Addigy
iOS, MacOS, Swift, AppKit, UIKit, SwiftUI, Continuous Integration (CI), MDM...
Persona Identities, Inc
iOS, iOS Native Libraries, Swift, UIKit, VisionKit, CocoaPods, Lottie...
Experience
- UIKit - 15 years
- iOS UI Design - 12 years
- Objective-C - 12 years
- Git - 10 years
- Swift - 8 years
- AppKit - 5 years
- SwiftUI - 4 years
- WatchOS - 3 years
Preferred Environment
Xcode, MacOS, Swift, SwiftUI, iOS
The most amazing...
...thing I've built recently is an end-to-end Swift app using server-side Swift on Linux, which provides the APIs used by an app on macOS and iOS.
Work Experience
Principal App Developer & Managing Director
2010 - PRESENT
jadehopper
- Founded an app development studio with my wife, and focused on building lovely apps that make life a little bit easier.
- Primarily took charge of consulting and contracting with clients.
- Developed some in-house apps, including Avoid Town and Bliss Yoga.
Technologies: RxSwift, WatchOS, Mobile Prototypes, UI Design, Git, Agile Software Development, Realm, CocoaPods, iOS UI Design, iOS SDK, Cocoa Touch, Xcode, iOS, User Experience (UX), UX Sketching, JavaScript, Ruby, Objective-C, Swift, RESTFul APIs, C, CI/CD Pipelines, Combine, API Integration, TestFlight, UI Animation, Claude, Keychain, Google Maps, Google Maps API, Code Review
Senior Swift Engineer
2011 - 2025
Addigy
- Modernized the UI/UX and further developed Addigy Self Service for macOS, including revamping and rearchitecting the existing codebase in Swift and using modern development best practices and standards.
- Migrated UI components to native Apple UI controls and fixed performance issues by ensuring tasks were executed on appropriate threads.
- Created a CI system to build, test, and deploy via GitHub Actions and transitioned app notarization to modern standards, including stapling.
- Integrated code coverage reporting to track and improve the test suite. Also integrated custom analytics to assist the product team.
- Led the development efforts to bring Self Service to iOS.
- Integrated Microsoft Authentication Library for conditional access.
- Migrated common use cases, UI components, and helpers to an internal Swift package that is now used by all Addigy apps.
- Developed the Managed App Config viewer app for iOS, which easily verifies and finds issues with MDM App Configurations, and built several internal macOS tools to assist the design team.
- Led the app engineering efforts behind building the new Addigy Assist app for macOS, a setup enhancement solution that simplifies the Mac setup process.
- Led the efforts on rearchitecting and modernizing the UX and UI for Addigy Identity, a native macOS app that simplifies the login experience.
Technologies: iOS, MacOS, Swift, AppKit, UIKit, SwiftUI, Continuous Integration (CI), MDM, Model View ViewModel (MVVM), Core Animation, CALayer, C, Objective-C, CI/CD Pipelines, Enterprise Distribution, API Integration, TestFlight, ChatGPT, UI Animation, Keychain, Code Review
Senior iOS Engineer
2019 - 2021
Persona Identities, Inc
- Developed the first version of the iOS SDK as a Swift framework that allows developers to easily integrate Persona’s best-in-class identity verification in their own apps.
- Contributed to this work, including API integration and using VisionKit to extract data from identity documents.
- Set up the CI pipeline to build, test, and deploy the SDK as a binary framework for easy integration with Swift Package Manager and CocoaPods.
- Developed a theming system to allow customers to adapt the SVG assets and Lottie animations to match their brand identity, as well as a sample iOS app.
Technologies: iOS, iOS Native Libraries, Swift, UIKit, VisionKit, CocoaPods, Lottie, SDK Development, TestFlight, UI Animation, Lottie-iOS, Code Review
Senior iOS Developer
2013 - 2020
Brainfeed LLC
- Developed an educational iOS app for kids featuring curated videos from all over the web.
- Built the iPhone and iPad app and the back-end publishing platform using Ruby and Sinatra.
- Contributed to the app, which was featured by Apple in several countries, including the iTunes Education Spotlight in May 2014, and reached number one in 67 countries.
Technologies: iOS, Objective-C, Swift, UIKit, Ruby, Sinatra, API Integration, In-app Purchases, TestFlight, StoreKit, UI Animation
iOS Developer
2019 - 2019
Duolingo, Inc.
- Worked with a variety of advertising platform SDKs to integrate advertising.
- Handled the implementation of A/B tests.
- Contributed to implementing UI experiments.
Technologies: iOS, Slack, GitHub, DoubleClick for Publishers, Google Ads API
Senior iOS Developer
2018 - 2019
Local Catch LLC.
- Led the UI effort on a 2-person team porting an existing Objective-C app to Swift, as well as adding additional features for enterprise distribution.
- Developed the build system for deploying via CI using BuddyBuild.
- Built a dashboard app for iPad with support for multiple displays to visualize real-time sales data and assisted with MDM deployment.
Technologies: iOS, Swift, Objective-C, UIKit, Core Graphics, Core Animation, REST, JSON, AirPlay, Realm, Enterprise Distribution, API Integration, Keychain
Senior iOS Developer
2017 - 2018
ribot
- Worked as part of the team developing the Vhi Mobile Health Assistant app for iOS for Irish healthcare provider and insurer Vhi Healthcare.
- Contributed to the app, which offers face-to-face video consultations with medical professionals, claiming medical expenses, and viewing coverage options.
- Mainly focused on leading the UI effort as well as creating custom components.
- Reached the number one spot on the Irish App Store.
Technologies: iOS, Swift, RxSwift, UIKit, Core Animation, API Integration, TestFlight, UI Animation, Keychain, Code Review
Senior Enterprise iOS Developer
2015 - 2017
June20, Inc.
- Developed an enterprise iPad app for a retail-focused startup that lets customers explore, compare, and configure products in-aisle using expanded content, videos, and reviews.
- Ensured that iPads were deployed to dozens of retail locations across North America and provisioned and configured via MDM.
- Contributed to the app, which ran in kiosk mode, and used a custom JavaScript framework for bidirectional communication with the dynamic content controlled and deployed server-side.
- Prototyped a customer-focused iPhone app that receives the information from in-store iPads to make an immediate purchase or take home for further consideration.
- Built a dashboard to check the physical location and statuses of the deployed devices in the field.
Technologies: Objective-C, JavaScript, iOS, HTML5, MDM, UIKit, Core Bluetooth, Core Motion, WebKit, API Integration, UI Animation, Keychain
Senior iOS Developer
2014 - 2015
ribot
- Worked as part of the team developing the Easyfundraising app for iPhone and iPad.
- Ensured the app offered a simple way of raising money while shopping online, providing customers an effortless way to help good causes and charities they care about.
- Focused mainly on implementing the user interface.
Technologies: iOS, Objective-C, UIKit, Core Animation, API Integration, UI Animation, Code Review
iOS Developer
2013 - 2013
ribot
- Led a team that developed an iOS app for a London-based chain of artisan coffee shops.
- Ensured the app implemented a loyalty card digitally and facilitated mobile payments.
- Focused mainly on developing the UI and implementing transitions and animations.
Technologies: iOS, Objective-C, UIKit, Core Animation, API Integration, UI Animation
iOS Developer
2012 - 2012
time:matters
- Contracted by time:matters (a subsidiary of Lufthansa Cargo) to develop a bespoke, enterprise app for employees, subcontractors, and customers.
- Ensured the app allowed tracking and tracing shipments of their spare parts, as well as same-day and emergency services.
- Built a custom Ruby-based back end to act as middleware between the iOS app and their existing package tracking system back end.
Technologies: iOS, UIKit, Objective-C, Ruby, API Integration, UI Animation
Mobile Application Developer
2011 - 2011
Flash on the Beach
- Developed the official conference guide for 2011, following the success of the 2009 and 2010 versions.
- Used traditional web technologies to deliver a solely mobile experience for iPhone, iPad, Android, and BlackBerry PlayBook.
- Added support for HTML5 AppCache to ensure the app could be used offline.
Technologies: HTML5, CSS, JavaScript, API Integration, UI Animation, Google Maps, Google Maps API
Playbook Application Developer
2011 - 2011
BlackBerry
- Worked on-site at QNX in Ottawa, developing first-party apps for the BlackBerry Playbook before it was launched.
- Implemented the user interface for the system browser and YouTube apps.
- Prototyped and implemented the user interface for the News app.
Technologies: Mobile App Development, Flash, ActionScript 3, Adobe AIR, UI Prototyping, UI Animation
Playbook Application Developer (3rd Party)
2010 - 2011
BlackBerry
- Worked for a company that was contracted by Research In Motion (now BlackBerry) to develop an app for Playbook OS, a new platform for their upcoming BlackBerry Playbook tablet.
- Collaborated closely with one of their London-based partners and their development team in building a custom third-party app.
- Led a small team of developers working on yet-to-be-released hardware before the tablet had been announced to the public.
Technologies: Flash, ActionScript 3, Adobe AIR
iOS Developer
2010 - 2010
Goodstuff
- Developed the first version of the “world’s first sneaker and street-wear city guide for iPhone”.
- Developed a custom data model syncing mechanism to ensure the client was always up to date.
- Contributed to the app, which got great reviews from folks who are really into their kicks.
Technologies: iOS, Objective-C, UIKit, API Integration, UI Animation
iOS Developer
2010 - 2010
ribot
- Developed the first version of an iOS app that enables grocery shopping on the go for Tesco, the grocery market leader in the UK.
- Contributed to the app, which climbed the UK App Store charts to reach the number one spot.
- Contributed to the effort, and after nine months of work, Tesco made its money back in one week.
Technologies: iOS, UIKit, Core Data, RESTFul APIs, API Integration, UI Animation
Flash Platform Specialist and iOS Developer
2008 - 2010
Tarantell AS
- Developed an iOS app to track the availability of city bikes in Oslo, Norway. Reached the #2 spot on the App Store.
- Built the 2009 conference guide for the Flash on the Beach international design and development conference. The app won bronze for Best Mobile Solution at Gulltaggen 2010.
- Developed a white-label recipe guide for the Norwegian Seafood Export Council.
- Developed several proofs of concept and mobile prototypes for Norwegian enterprise clients.
Technologies: Mobile Prototypes, UI Design, Git, CocoaPods, iOS UI Design, Cocoa Touch, Xcode, iOS, User Experience (UX), UX Sketching, Ruby, JavaScript, Objective-C, RESTFul APIs, API Integration, UI Animation
ActionScript Developer
2007 - 2008
Blogform Digital Magazines GmbH
- Led a team of designers and developers in creating a new magazine engine with Flex using Cairngorm.
- Maintained and further developed the previous AS2 engine and introduced open-source tools to improve production workflow.
- Introduced and trained colleagues in object-oriented programming and ActionScript best practices.
- Created interactive magazine content for clients such as Netcom, SAS, Swarovski, TubeTheVote, the New York Giants, the Kentucky Derby, Nickelodeon, and several Time, Inc. properties such as People Magazine, People en Español, and InStyle.
Technologies: UI Design, Agile Software Development, User Experience (UX), Cairngorm, Flex, RESTFul APIs, API Integration, UI Animation
Flash Developer
2005 - 2007
Nordic Lottery Systems AS
- Developed Flash-based games and modules as well as an ActionScript framework for use in a global gaming portal.
- Developed Flash-based casino betting games using Flash Remoting and integrated these with Java-based gaming portals.
- Further developed Flash-based platforms for scratch-and-win and quiz games used by an advertising agency for several Norwegian newspapers and organizations.
Technologies: UI Design, Agile Software Development, User Experience (UX), Flash, RESTFul APIs, API Integration, UI Animation
Systems Developer
2004 - 2005
Wide Computing AS
- Further developed an eCommerce web service for Overture featuring paid inclusion subscriptions using Perl and SOAP.
- Developed front ends for this service for both the company website and for integration at a partner ISP using C# and ASP.NET.
- Developed a W3C standards-compliant web publishing system and several dHTML-based web applications for the support department and scripts to handle back-end routines.
Technologies: XSLT, XML, CSS, HTML, JavaScript, C#, Perl
Experience
Avoid Town
Cruise ships visit the Cayman Islands on a regular basis, and the thousands of passengers they bring in every day are an important part of the islands' tourism product. However, for residents, lots of ships also means loads of traffic downtown.
Wouldn’t it be nice if you could check how busy the town would be? And if you’re in a rush, maybe you should avoid town entirely? There should be an app for that, right?
Yep, we thought so too! Check Avoid Town before you leave, and don't get caught out again.
Wouldn’t it be nice if you could check how busy the town would be? And if you’re in a rush, maybe you should avoid town entirely? There should be an app for that, right?
Yep, we thought so too! Check Avoid Town before you leave, and don't get caught out again.
Bliss Yoga
Get your yoga pants ready and dust off your mat! With the new app for the Bliss Yoga Cayman studio, you can easily find your next class. Whether it be an intense Power session, an energetic Flow sequence, or something a little more relaxing, Bliss has you covered.
Brainfeed
Brainfeed is an educational iPad app for kids seven years old and older. Behind the scenes, a team sifts through the massive amounts of video available on the web and curates the very best educational videos that are both age-appropriate and curriculum-based.
The result is content that engages kids and is both animation-rich and of high visual quality. The best of the web, in a kid-friendly package.
The result is content that engages kids and is both animation-rich and of high visual quality. The best of the web, in a kid-friendly package.
Here
Here was an iPhone app that makes sharing your location super simple. Your contacts don't even have to have the app installed or even own an iPhone. The app was Sherlocked by iOS 17, which has this functionality built into Messages.
Tesco Groceries
The first version of an iOS app that enables grocery shopping on the go for the grocery market leader in the UK, reaching the number one spot on the UK App Store. After nine months of work, Tesco made its money back in one week.
Bysykkel App
I developed this iPhone app back in 2009. It found city bikes close to you in Oslo, allowed you to find city bike stations located around the city, and told you how many bikes or locks were available (to return your bike).
Scanner
Hired by time:matters, a company of Lufthansa Cargo, to develop Scanner in 2012. This is an app for time:matters employees, subcontractors, and customers to track and trace shipments of their spare parts, same-day, and emergency services.
I also built a custom Ruby-based back end to act as middleware between the app and their existing package tracking system.
I also built a custom Ruby-based back end to act as middleware between the app and their existing package tracking system.
FOTB 2010
We built the official conference iPhone app for the lovely Flash on the Beach conference in 2010. Browse through the talks and add them to your own custom schedule. Read about the speakers and find conference locations near you. Also, check out what people are saying about the conference in the Twitterverse.
FOTB 2009
We built the official conference iPhone app for the most excellent Flash on the Beach conference in 2009. Browse through the talks and add them to your own custom schedule. Read about the speakers and find conference locations near you.
Education
2000 - 2004
Bachelor of Science Degree in Computer Science
University of Oslo - Oslo, Norway
Skills
Libraries/APIs
CocoaPods, Core Graphics, Core Animation, Firebase iOS SDK, X (formerly Twitter) API, Facebook API, Lottie-iOS, Google Maps, Google Maps API, RxSwift, X (formerly Twitter) SDK, Google Ads API, iOS Native Libraries
Tools
Xcode, TestFlight, Claude, Git, Travis CI, ChatGPT, Flash, Adobe AIR, Slack, GitHub
Languages
Swift, Objective-C, ActionScript 3, HTML5, AppleScript, Ruby, JavaScript, Perl, C#, HTML, CSS, XML, XSLT, C
Frameworks
Cocoa Touch, iOS SDK, UIKit, SwiftUI, AppKit, Core Location, MapKit, Combine, Core Bluetooth, Core Motion, StoreKit, Flex, Cairngorm, Sinatra, Core Data, Adobe Flex
Paradigms
iOS UI Design, REST, Model View ViewModel (MVVM), Agile Software Development, UI Design, Continuous Integration (CI)
Platforms
MacOS, iOS, Keychain, WatchOS, tvOS, Bluetooth Low Energy (LE), Bitrise, Heroku, Firebase
Storage
Realm, MySQL, Amazon S3 (AWS S3), JSON
Other
Mobile Prototypes, User Experience (UX), UX Sketching, GitHub Actions, RESTFul APIs, CALayer, iPadOS, APNs, Mobile App Development, UI Prototyping, WebKit, Enterprise Distribution, API Integration, In-app Purchases, UI Animation, Code Review, Bluetooth Beacons, AVFoundation, CI/CD Pipelines, MDM, Computer Science, AirPlay, DoubleClick for Publishers, VisionKit, Lottie, SDK Development
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