Rebuilding Citizens Bank's iOS App with Backbase

Citizens Bank, one of the largest retail banks in the United States with over $200 billion in assets, needed to modernize their iOS mobile banking application. The existing app had accumulated years of technical debt and couldn't keep pace with customer expectations for modern digital banking experiences. I joined the project to help rebuild the app from the ground up using Backbase's banking SDK and modern Swift architecture.

The Challenge

The legacy Citizens Bank iOS app faced several critical issues:

• Aging Objective-C codebase with inconsistent patterns
• Tightly coupled architecture making feature development slow
• Limited ability to leverage Backbase platform capabilities
• Poor testability leading to regression issues
• Inconsistent UI that didn't match modern banking app expectations

The goal was a complete rewrite that would provide a foundation for rapid feature development while maintaining the security and reliability requirements of a major financial institution.

Backbase Integration

Backbase provides a comprehensive digital banking platform that accelerates mobile development. Our integration strategy focused on leveraging Backbase's strengths while maintaining flexibility:

Backbase SDK Components:

• Identity & Access Management for secure authentication
• Retail Banking widgets for accounts, transactions, and payments
• Journey orchestration for complex user flows
• Design System foundation for consistent UI

Customization Layer:

• Custom Swift wrappers around Backbase modules
• Bank-specific business logic isolated from SDK
• White-label theming matching Citizens Bank brand
• Analytics integration for user behavior tracking

Architecture

We implemented a clean MVVM architecture that integrated seamlessly with Backbase:

Presentation Layer:

• SwiftUI views for new screens
• UIKit integration for Backbase widgets
• Combine-based data binding
• Coordinator pattern for navigation

Domain Layer:

• Use cases encapsulating business logic
• Repository protocols for data abstraction
• Domain models independent of Backbase DTOs

Data Layer:

• Backbase SDK as primary data source
• Secure token management with Keychain
• Offline caching for critical data
• Network monitoring and retry logic

Security Implementation

Banking apps require exceptional security measures:

Authentication:

• Biometric authentication (Face ID / Touch ID)
• Multi-factor authentication flows
• Session management with secure token refresh
• Jailbreak and tampering detection

Data Protection:

• Certificate pinning for all API communication
• Encryption at rest for sensitive data
• Secure Enclave integration for keys
• Runtime application self-protection (RASP)

Compliance:

• WCAG 2.1 AA accessibility compliance
• SOC 2 audit requirements
• PCI DSS considerations for payment flows

Development Practices

The project followed rigorous development practices appropriate for financial software:

Code Quality:

• Comprehensive unit test coverage (>80%)
• UI testing for critical user journeys
• SwiftLint enforcement for code consistency
• Pull request reviews with security checklist

CI/CD Pipeline:

• Automated builds on every commit
• Test suite execution with coverage reporting
• Static analysis and security scanning
• Beta distribution through TestFlight

Collaboration:

• Close partnership with Backbase technical team
• Regular sync with Citizens Bank product owners
• Agile sprints with bi-weekly releases

Results

The rebuilt app delivered significant improvements:

• 50% faster average screen load times
• 4.8 star App Store rating (up from 3.2)
• 60% reduction in crash reports
• 3x faster feature development velocity
• Improved accessibility scores across all flows

The modernized Citizens Bank iOS app now serves millions of customers with a reliable, secure, and delightful mobile banking experience.