Brandon Mantzey

Senior iOS Engineer

Built applications serving 30M+ users across financial services, wearables, and agriculture

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Featured Projects

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SwiftFolio

Independent Development

Professional portfolio iOS application built with modern SwiftUI and Firebase backend. Comprehensive TDD approach with full CI/CD pipeline via Xcode Cloud. Demonstrates mastery of current iOS development stack and DevOps practices.

SwiftUI Firebase TDD Xcode Cloud
  • Built with SwiftUI from ground up demonstrating modern declarative UI development
  • Firebase integration: Authentication, Firestore database, Cloud Hosting for dynamic content
  • Test-driven development with Swift Testing ensuring code quality and reliability
  • Interactive map with guestbook functionality using real-time Firestore synchronization
  • PDF viewer system pulling always-current resume from Firebase Hosting
  • Complete CI/CD pipeline with Xcode Cloud, GitHub integration, and automated TestFlight deployment
  • Jira project management and Agile methodology applied to solo project development
View on GitHub
Garmin Dive

Garmin Dive

Garmin International

Dual-platform diving application with 4.8-star App Store rating and 30+ language support. Learned Android/Kotlin from scratch, achieving productivity parity with iOS despite 10+ years iOS background. Significant contributor to initial app launch.

Swift + Kotlin MVVM Bluetooth (BLE) GraphQL
  • Developed features simultaneously across iOS (Swift) and Android (Kotlin) maintaining platform parity
  • Integrated Garmin's proprietary Bluetooth SDKs (GFDI, MultiLink) for dive computer synchronization
  • Implemented Apollo GraphQL for real-time backend synchronization with offline-first Realm database
  • Built comprehensive Firebase integration (Analytics, Crashlytics, Remote Config, Performance)
  • Delivered production app with 4.8-star rating serving global scuba diving community
  • Adapted to rigorous code review standards and TDD practices using Quick/Nimble frameworks
View on App Store
FieldNET Mobile

FieldNET Mobile

Lindsay Corporation

Complete flagship iOS app rewrite from screenshots only. Delivered MVP ahead of schedule earning CEO recognition at awards banquet. Serves hundreds of thousands of agriculture professionals worldwide controlling Zimmatic pivot irrigation systems.

Clean Swift (VIP) Core Data IoT MapKit
  • Clean Swift Architecture (VIP) pattern demonstrating scalable architecture ownership
  • Built offline-first system enabling reliable operation in remote agricultural locations without connectivity
  • Implemented Variable Rate Irrigation (VRI) control for precision agriculture and water conservation
  • Collaborated with backend team optimizing API schemas for mobile consumption and server performance
  • Led Android consultant team maintaining feature parity across platforms
  • 6-language localization supporting global agricultural markets
View on App Store
Transition Hub

Transition Hub CMS

Perficient | TD Ameritrade / Charles Schwab

Pioneered dynamic CMS messaging system facilitating migration of 30M+ TD Ameritrade customers to Charles Schwab. Business-controlled content delivery eliminating need for app redeployment.

Swift Firebase CMS Architecture XML/JSON Flutterflow
  • Architected XML/JSON-based messaging system giving business complete control over customer communications without engineering intervention
  • Maintained 3 iOS applications simultaneously (TDA Mobile, TDA Authenticator, Schwab Mobile) serving 13.5M+ users
  • System praised as "essential to delivering phase of transition hub on time" with "almost no issues"
  • Implemented Firebase Analytics providing clickstream data for user behavior analysis
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Particle System

Multi-Platform Graphics Tool

Visual particle effects editor spanning three iterations: XNA/DirectX (2006), OpenGL/Mac (2009), and now Metal/SwiftUI. Cross-platform tool enabling real-time particle design with binary export for game engine integration.

Metal Swift SwiftUI Graphics Programming
  • Original system: Created with XNA Framework and DirectX using C# at Full Sail University (2006)
  • First production use: Ported to OpenGL/Objective-C Mac app for Wild Wild Train iOS game at Stratogon (2009)
  • Current iteration: Complete rewrite using Apple Metal, Swift, and SwiftUI for modern macOS and iOS
  • Leverages knowledge from two previous iterations while reusing critical optimization components
  • Multi-platform architecture supporting both Mac and iOS from single codebase
  • Features texture import, real-time particle preview, and binary export format for game engine integration
  • Learning-focused development: Using ChatGPT as guide to master Metal graphics pipeline and modern best practices
  • Demonstrates evolution of graphics programming expertise across 18+ years and multiple technology stacks
View on GitHub

Professional Journey

1998-2004

US Air Force, Active Duty

Electronics & satellite communications • 3x top graduate • Earned two Associates degrees

2004-2006

US Air Force, Reserves

Transitioned to education focus

2006-2008

Full Sail University

Bachelor's in Game Development • Studied under OpenGL Superbible author

2008-2011

Early iOS Pioneer

Game engine from scratch • Agency work • DoD contracting (Java EE, JavaScript)

2011-2015

Enterprise Pharmaceutical

iOS Lead • FDA-compliant systems • 16-language localization

2015-2024

Senior iOS Roles

Agriculture IoT • Wearables • Financial Services (30M+ users)

2024-Present

Independent Development

Modern stack mastery • SwiftUI • Firebase • Cross-platform

Technical Expertise

Languages: Swift • Objective-C • C • C++
Frameworks: UIKit • SwiftUI • Core Data • Combine • MapKit • Core Location • Core Animation • Core Graphics
Tools: Xcode • Interface Builder • Instruments • TestFlight • App Store Connect
Patterns: Clean Swift Architecture (VIP) • MVVM • Coordinator • MVC • Protocol-Oriented Programming • Object-Oriented Programming
Principles: SOLID • Dependency Injection • Repository Pattern • Factory Pattern • Observer Pattern
Android: Kotlin • Android SDK • Android Studio • Gradle
Other: Flutter/Dart (certified) • JavaScript • Java
Networking: REST • GraphQL • Alamofire • URLSession
Data: JSON • XML • OAuth2
Cloud: Firebase (Analytics, Crashlytics, Firestore, Auth, Hosting)
iOS: Core Data • Realm • UserDefaults • Keychain • NSCoding • Codable
Database: SQLite • Firebase Firestore • Offline-first architecture
Testing: Swift Testing • XCTest • TDD • Unit Testing
CI/CD: Jenkins • Xcode Cloud • GitHub Actions • TestFlight automation
Version Control: Git • GitHub • Bitbucket • Mercurial • SVN
Bluetooth: BLE (Bluetooth Low Energy) • External Accessory Framework • Proprietary SDKs
Sensors: Core Location • Camera • Photo Library
iOS Graphics: Core Graphics • Core Animation • Custom Drawing
Game Graphics: DirectX • OpenGL • OpenGL ES • THREE.js • Particle Systems

Let's Connect

Available for senior iOS engineering opportunities and consulting engagements.

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