What are the responsibilities and job description for the Senior iOS Developer position at shift4?
Overview
Shift4 (NYSE: FOUR) is boldly redefining commerce by simplifying complex payments ecosystems across the world. As the leader in commerce-enabling technology, Shift4 powers billions of transactions annually for hundreds of thousands of businesses in virtually every industry. For more information, visit www.shift4.com.
Senior iOS Developer
Shift4 is expanding globally and we are seeking a Senior iOS Developer to be a key member of a high-velocity engineering team. In this role, you will work hands-on with our iOS platform and tech stack to design, develop, and maintain high-quality, performant mobile features. You will collaborate closely with engineering leadership, product, and design teams to ensure alignment with business needs and deliver robust, user-centric solutions. As a Senior iOS Developer, you will mentor junior engineers, champion code quality, address technical debt, and help drive the modernization of our iOS codebase. If you’re passionate about crafting world-class iOS experiences, mentoring the next generation of mobile engineers, and pushing the boundaries of what’s possible on Apple platforms, this may be the ideal opportunity for you!
This role is onsite based at either of the following Shift4 locations: Atlanta, GA or Butler, PA
Responsibilities
- Feature Development & Technical Leadership: Build and ship high-quality iOS features using Swift, Objective-C and the modern iOS ecosystem, resolve complex issues, and uphold engineering best practices and coding standards.
- Architecture & Design: Partner with tech leads and engineering leadership to define and evolve the iOS architecture, ensuring scalability, performance, and maintainability.
- System Debugging & Support: Diagnose and resolve production issues in collaboration with backend and DevOps teams, providing Level 3 support for critical iOS incidents when needed.
- Technical Expertise: Become a domain expert in key areas of the iOS platform and drive technical debt reduction, refactoring, and modernization efforts (e.g., SwiftUI adoption, modularization, performance optimization).
- Collaboration & Alignment: Work closely with product managers, designers, backend engineers, and QA to deeply understand requirements, deliver pixel-perfect experiences, and align with business goals.
- Mentorship & Development: Mentor junior and mid-level iOS engineers, conduct code reviews, and foster their technical growth within the team.
- Process Improvement: Continuously improve engineering processes, CI/CD pipelines, testing strategies, and iOS development best practices.
Qualifications
Experience:
- 5 years of professional iOS development experience and a total of at least 8 years of experience as a Software Engineer
- 4 years of deep expertise in Swift and Objective-C is required.
- Proven track record of leading complex feature development and architectural improvements on large-scale iOS codebases.
Technical Skills:
- Mastery of Swift and modern iOS frameworks (SwiftUI, Combine, Async/Await).
- Strong experience with UIKit, SQLite and networking layers (URLSession, Alamofire, etc.).
- Expertise in iOS architecture patterns (MVVM, Clean Architecture, VIPER, or modular design).
- Proficiency with Apple’s development tools (Xcode, Instruments, TestFlight) and CI/CD pipelines (Fastlane, CircleCI, Jenkins).
- Familiarity with backend integration (REST/GraphQL APIs, authentication flows, WebSocket).
- Experience with App Store submission process, code signing, provisioning, and distribution.
- Knowledge of performance profiling, memory management, and battery optimization on iOS devices.
- Comfortable working with globally distributed teams.
Preferred Skills (Additional experience that is a plus to have):
- Experience with AWS or other cloud environments (monitoring, logging, crash reporting tools).
- AI software development experience specially AI agents, Claude Code, etc.
- Experience with unit testing (XCTest, Quick/Nimble) and UI testing; knowledge of snapshot testing.
- Experience building consumer-facing or enterprise iOS apps in point-of-sale, hospitality, retail, payments, or fintech domains.
Education:
- Bachelor’s degree in Computer Science, Engineering, or equivalent practical experience.
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We are an Equal Opportunity Employer and do not discriminate against any employee or applicant for employment because of race, color, sex, age, national origin, religion, sexual orientation, gender identity and/or expression, status as a veteran, and basis of disability or any other federal, state or local protected class.