Sr Software Engineer, iOS

T-Mobile•Bellevue, WA

1d•$113,600 - $205,000•Onsite

About The Position

We are seeking a highly skilled and motivated iOS Sr. Software Engineer to join the team powering the T-Life app—T-Mobile's flagship mobile experience. In this role, you will contribute to the design, development, and delivery of high-quality, performant, and AI-enabled iOS features that reach millions of users. The Sr. Software Engineer is essential for designing, implementing, and deploying scalable mobile software solutions that meet customer requirements and support high-availability environments. This role focuses on iOS application development within established architecture, collaborating with cross-functional engineering teams to build modern, reliable features and integrate backend services—including AI-powered capabilities. Success is measured by the ability to deliver dependable technical solutions, produce clear documentation, and contribute to continuous improvement and innovation that enhances customer experience and supports business goals.

Requirements

Bachelor's Degree plus 5 years of related work experience; OR advanced degree with 3 years of related experience.
Acceptable areas of study include Computer Science, Software Engineering, Information Management, or equivalent experience in field.
4–7 years of technical engineering experience.
Proficiency in Swift and familiarity with Objective-C for legacy code maintenance.
Experience with UIKit and/or SwiftUI for building production-grade iOS interfaces.
Strong understanding of iOS app lifecycle, memory management (ARC), and performance optimization.
Experience integrating RESTful APIs using async networking patterns (URLSession, Combine, async/await).
Familiarity with dependency management tools (Swift Package Manager, CocoaPods).
Experience working with Git-based workflows and collaborative code review processes.
Foundational exposure to AI-enabled backend services (e.g., LLM-backed APIs, personalization or recommendation systems).
Communication
Customer Service
Analytics
Technical Writing
At least 18 years of age
Legally authorized to work in the United States

Nice To Haves

Experience with SwiftUI for building modern, declarative iOS interfaces.
Proficiency with Swift Concurrency (async/await) and/or Combine for reactive and asynchronous programming.
Experience with architectural patterns such as MVVM, MVC, or Coordinator.
Experience integrating RESTful APIs and backend services that support personalization or intelligent user journeys.
Exposure to AI-powered APIs, LLM-backed services, inference endpoints, or recommendation systems.
Familiarity with AI-assisted development tools (e.g., GitHub Copilot, ChatGPT Enterprise, Claude) to accelerate coding, documentation, and code review workflows.
Knowledge of iOS accessibility standards and implementation (e.g., VoiceOver, Dynamic Type).
Experience with CI/CD tools for iOS (e.g., Fastlane, Xcode Cloud, TestFlight).
Familiarity with performance profiling tools (e.g., Instruments, MetricKit).
Experience working in Agile/Scrum development environments.

Responsibilities

Develop software solutions and conduct tests to drive engineering projects and ensure quality deliverables, including design and development of scalable iOS features using Swift and modern Apple frameworks.
Contribute to design innovations that improve systems, processes, or services using new frameworks, architectural patterns such as MVVM or Coordinator, and industry best practices.
Collaborate with technical teams to deliver solutions and mentor others through knowledge sharing and training sessions, including guidance on mobile engineering standards and AI-enabled feature integration.
Support technology strategy by evaluating and applying current iOS technologies and mobile development trends that align with business goals.
Create clear documentation for software code, system designs, and business requirements to support knowledge sharing and cross-team collaboration.
Lead medium-to-large iOS initiatives, contribute to architectural decisions, and promote scalable, secure, and maintainable mobile application design.
Integrate RESTful APIs and backend services, including AI-powered services that enable personalization, conversational experiences, recommendations, and intelligent automation.
Ensure quality through strong unit testing, performance optimization, CI/CD participation, and adherence to security and App Store compliance standards.
Mentor and coach junior engineers while providing technical leadership across cross-functional teams, promoting knowledge sharing, engineering best practices, operational excellence, and a culture of accountability and continuous improvement.
Drive execution of daily operational activities, incident remediation, and service improvement initiatives, ensuring projects and operational commitments are successfully delivered through implementation, stabilization, and ongoing support.
Also responsible for other duties/projects as assigned by business management as needed.