Pablo is available for hire
Hire PabloPablo Carcelén
Verified Expert in Engineering
Cryptography Developer
Location
Madrid, Spain
Toptal Member Since
October 1, 2018
Pablo is an iOS developer who loves a challenge, keeps up to date with the latest technologies, and strives for constant improvement in his knowledge and techniques. He is proactive and impact-driven. Past projects include EPUB and PDF e-reader projects and technologies, such as web sockets, HLS, and multicast UDP. The biggest app he's worked on has over 10 million customers.
Portfolio
Nueon Inc.
Amazon Web Services (AWS), Kubernetes, Docker, SwiftUI...
Tuenti (Telefonica)
Swift, Objective-C, iOS
BQ
Swift, Objective-C, Multicast, Encryption, PDF, EPUB, iOS
Experience
Availability
Part-time
Preferred Environment
Slack, Jira, Git, Jenkins, Xcode, MacOS
The most amazing...
...project I've worked on generated G-code (a CNC language) from an STL and drew paths that a 3D-printer would take using Apple's Metal APIs.
Work Experience
Head of Software
2019 - PRESENT
Nueon Inc.
- Developed an iOS app in SwiftUI with custom charts and complex UI elements.
- Designed and developed a protocol over Bluetooth Low Energy (LE) to pair an accessory to the app.
- Designed a system to invite members to peer-to-peer using Bluetooth LE.
- Implemented and deployed a push notification server using Swift for Linux that connects to APNs via HTTP/2. The server polls an AWS SQS queue and processes feedback responses. The component is Dockerized and deployed in a Kubernetes cluster.
- Implemented a survey component inside the app that had a tree-like structure and could have branches and reusable sub-question for a given question depending on the answer.
- Implemented an image processing system in the back end and app to optimize images, reduce latency and minimize load times, including using a CDN, an on-the-fly resizing server, and developing preloading strategies in the app.
Technologies: Amazon Web Services (AWS), Kubernetes, Docker, SwiftUI, Amazon Simple Queue Service (SQS), Amazon DynamoDB, Java, Spring, MacOS, iPadOS, WatchOS, iOS, Swift
Senior iOS Engineer
2017 - 2020
Tuenti (Telefonica)
- Worked as a core engineer for an iOS app with over 20 million users.
- Made the project compile three times faster.
- Modularized the iOS project extensively into frameworks, so the work was more sandboxed and supported rich extensions.
- Added support for accessibility and dynamic type using our font toolkit.
- Developed automated release generation in CI and made other improvements.
- Improved multi-branding support so that brands can link against a different number of frameworks (instead of only disabling a feature on runtime).
Technologies: Swift, Objective-C, iOS
iOS Tech Lead
2014 - 2016
BQ
- Developed a PDF reader that supported features such as links, ToC, and text search.
- Developed the native side of an EPUB reader.
- Developed a plug-in architecture to share features between both readers.
- Developed the DRM system for both iOS and Android through a C common implementation.
- Worked on an IoT project and developed custom UI animated components.
- Joined Apple's MFi program and studied the specifications for both a HomeKit product, and a Bluetooth (non-BTLE) robot.
- Developed the tools/architecture needed to decrypt books on the fly over encrypted zips, PDFs, etc. (previously they were being decrypted on disk).
- Deployed a distributed (using ZeroMQ) stress testing tool using Locust for simulating complex flows in order to stress-test the back-end.
- Worked on a prototype of a 3D printer app to convert models in STL to G-Code (the language 3D printers understand). And be able to draw the visualization of the path the printer would take using Apple Metal.
Technologies: Swift, Objective-C, Multicast, Encryption, PDF, EPUB, iOS
iOS Engineer
2013 - 2014
Welvi Experience
- Developed a personal training app.
- Created a UI toolkit to support the extensive custom UI the app had.
Technologies: Objective-C, iOS
iOS Engineering Intern
2013 - 2013
Creania Labs
- Built a radio app with HLS streams.
- Helped set up the HLS server.
- Built the iOS SDK for a tracking service specialized in music called Voizzup.
- Built a prototype for Life Fitness for integrating our technology with their fitness equipment.
Technologies: Objective-C, iOS
Experience
Tuenti • Movistar • O2 • MeuVivo
These apps power Telefonica's most important brands.
I work in the Apps Core team, charged with:
• Platform evolution (app architecture, building blocks for other teams, adopting new iOS and Swift features, etc.).
• Testing platform.
• Automating releases.
• Multibranding support.
• API.
• Persistence.
• Security.
I work in the Apps Core team, charged with:
• Platform evolution (app architecture, building blocks for other teams, adopting new iOS and Swift features, etc.).
• Testing platform.
• Automating releases.
• Multibranding support.
• API.
• Persistence.
• Security.
Ebooks
Ebooks is a white label app for reading and discovering books. It is the same concept as Spotify or Netflix applied to books.
I was the iOS tech lead of a team of five.
The app was technically challenging as it involved:
- Syncing content such as the library, notes, reading progress
- DRM and cryptography
- Knowing the EPUB specs and interoperating with the JS reader (also created in-house). The app was in charge of parsing metadata of the EPUB and also coordinating the readers in several WKWebViews, taking snapshots for having smooth transitions, etc. The experience was very similar to iBooks (with the page flip transition).
- Implementing a high-performance PDF reader, with accessibility features, terms of contents, and link support.
I was the iOS tech lead of a team of five.
The app was technically challenging as it involved:
- Syncing content such as the library, notes, reading progress
- DRM and cryptography
- Knowing the EPUB specs and interoperating with the JS reader (also created in-house). The app was in charge of parsing metadata of the EPUB and also coordinating the readers in several WKWebViews, taking snapshots for having smooth transitions, etc. The experience was very similar to iBooks (with the page flip transition).
- Implementing a high-performance PDF reader, with accessibility features, terms of contents, and link support.
HALU
HALU is BQ’s first IoT project. It is a smart lamp system where lamps form a p2p mesh.
The iOS app:
- Has custom controls and animations for controlling color, brightness.
- Has a complex wizard for setting up the lamps.
- Uses ReactiveCocoa for listening to notifications in the network (sent by the lamps via UDP), and for helping with communication with the lamps.
The iOS app:
- Has custom controls and animations for controlling color, brightness.
- Has a complex wizard for setting up the lamps.
- Uses ReactiveCocoa for listening to notifications in the network (sent by the lamps via UDP), and for helping with communication with the lamps.
Welvi
Welvi is an app that helps users keep a healthy lifestyle. It features customized training with professionals and nutrition programs. Welvi achieved 100,000 downloads on the first day.
I was the main iOS developer. The main challenge of this app was its unique UI, with custom components and transitions.
I was the main iOS developer. The main challenge of this app was its unique UI, with custom components and transitions.
MegaStar FM
MegaStar FM is a radio app based on HLS technology. The app had lyric support and changed the theme based on the song that was playing.
MegaStar is owned by Grupo COPE and has more than 200k daily listeners
I co-developed the app with another peer, I focused on internals like:
- API support
- HLS (HTTP Live Stream) support with adaptive quality depending on user preference and network conditions
- Lyric support
MegaStar is owned by Grupo COPE and has more than 200k daily listeners
I co-developed the app with another peer, I focused on internals like:
- API support
- HLS (HTTP Live Stream) support with adaptive quality depending on user preference and network conditions
- Lyric support
Education
2011 - 2015
Bachelor's Degree in Software Engineering
Universidad Politécnica de Madrid (UPM) - Madrid, Spain
Skills
Libraries/APIs
Core Animation, Core Graphics, RxSwift
Tools
Fastlane, Xcode, Xcode Playgrounds, Jira, Git, Slack, Amazon Simple Queue Service (SQS), Jenkins
Frameworks
SwiftUI, Core Data, ReactiveCocoa, Spring, Combine
Languages
Swift, Objective-C, C, SQL, C++, Java, Go
Platforms
iOS, WatchOS, Docker, Kubernetes, Amazon Web Services (AWS), MacOS
Paradigms
Testing, Unit Testing, Functional Programming, Acceptance Testing
Storage
SQLite, Amazon DynamoDB, Redis, MongoDB
Other
Concurrency, Encryption, Multicast, iPadOS, Cryptography, Networks, Data Compression, EPUB, PDF, HTTP Live Streaming (HLS), CI/CD Pipelines
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