Juegos ONCE

The challenge

The Juegos ONCE iOS team (ZEAL Network SE) maintained a business-critical, high-traffic production app built on a mature UIKit codebase. The pressure came from two directions: delivering new features and modernising the architecture — without ever risking production stability — while simultaneously maintaining and improving iOS accessibility. ONCE is Spain's leading organisation for people with visual impairments, and the app had to work flawlessly with VoiceOver. Accessibility here was not a nice-to-have; it was a core product requirement.

The solution

AtalayaSoft assigned Francisco José García Navarro as a senior iOS engineer embedded in the Juegos ONCE product team. His work covered three parallel fronts:

1. Maintenance and continuous evolution

As a senior iOS engineer integrated into the team, Francisco took ownership of the continuous evolution of a high-traffic production app:

• Resolving functional bugs in production.
• Developing new features and screens.
• Refactoring and modernising legacy code.
• Updating the app to support new iOS versions.
• Code reviews to maintain quality standards across every iteration.
• Automated testing with XCTest + UI/snapshot to prevent regressions.

2. Progressive UIKit → SwiftUI migration

The Juegos ONCE codebase was built on UIKit. Migrating to SwiftUI on an active app required a low-risk, incremental approach:

• SwiftUI adoption module by module, coexisting with UIKit.
• Clean Architecture principles applied to reduce coupling and improve long-term testability.

3. iOS Accessibility as a first-class concern

Given ONCE's mission around visual impairment, iOS accessibility was a non-negotiable product requirement:

• Improving usability for VoiceOver users.
• Reviewing accessibility labels, hints, and focus order across existing screens.
• Validating every new feature with assistive technologies before release.

Technical highlights

Clean Architecture migration without disrupting production

The app had a legacy architecture that made adding features without regressions difficult. Francisco applied Clean Architecture progressively — separating data, domain, and presentation layers — enabling safer product evolution without a full rewrite.

VoiceOver accessibility in a high-traffic production app

Improving accessibility in an active production app is significantly more complex than building it in from scratch: every change must be compatible with existing flows and validated with VoiceOver on real devices. Francisco raised the accessibility bar in line with ONCE's institutional commitment to inclusive digital products, while keeping the app stable throughout.