Andrew Tenno

Staff Mobile Engineer at Meta, promoted from E4 to E6, building iOS and React Native platform infrastructure that powers 500M+ video calls per month across Messenger and Instagram. 11+ years of production experience spanning Swift, SwiftUI, UIKit, React Native, Android (Kotlin + Jetpack Compose), real-time AR rendering, WebRTC video infrastructure, and cross-platform SDK engineering, with security-first mobile architecture across Keychain, certificate pinning, and on-device encryption. Two open-source React Native patches merged to main, technical writing cited by iOS Weekly, and conference speaker on mobile performance at scale.

Staff Software Engineer - iOS - Meta - San Francisco, CA

(2019-10)

E4 → E5 → E6

• Eliminated 3 - 5ms per-frame GPU overhead and architected Messenger's full AR rendering pipeline (Metal + ARKit + Core ML), shipped as the AR Effects SDK across Messenger, Instagram, and Portal, cutting per-filter development time by 40% and QA surface in half.
• Segmentation pipeline runs on Neural Engine in under 6ms on A14+, achieving sub-16ms end-to-end latency on iPhone 12+ through device-adaptive model routing and thermal-adaptive quality tiers.
• Led rsys WebRTC integration and built a proactive NWPathMonitor ICE restart state machine that cut reconnect failures by 25% and call setup latency by 30%.
• Shipped Messenger Group AR Effects (Oct 2021) with ML-ranked prefetch and RTCDataChannel sync; AI-powered recommendations cut picker load time by 60% for returning users.
• Rebuilt the AR effects UI in SwiftUI using @StateObject, matched geometry, and UIHostingController with Combine state sync, then authored the UIKit integration guide adopted across the calling org.
• Set cross-team technical standards through 3 canonical design docs and bi-weekly architecture office hours across 3 iOS org teams, mentoring 4 engineers with one promoted to E5 in 14 months.
• Authored Messenger's native module suite (iOS RCTBridgeModule + Kotlin Android counterparts), identified a serialization hotspot through bridge performance instrumentation, and resolved it with RCTEventCoalescer, cutting bridge crossings by 85% and JS thread utilization by 20%.
• Designed and owned the full mobile CI/CD pipeline covering Xcode Cloud, GitHub Actions, Fastlane Match with App Store Connect API, and Firebase Test Lab, compressing release cycle from 3 days to same-day automated delivery.
• Built the cross-platform RN component library and reduced per-feature UI dev time by 35% across teams shipping simultaneous iOS and Android features.
• Drove Jetpack Compose adoption on Messenger Android, shipping 3 production screens built with Coroutines, StateFlow, and ViewModel, with the Compose migration guide adopted by 2 additional Android teams.
• Co-led Messenger's Swift adoption program using Python and libclang AST tooling, an internal Swift style guide, and a migration framework rolled out across 8 teams, growing Swift LOC from 15% to 45% in 18 months.
• Built a custom ObjC/Swift bridging test harness with XCTest and XCTMemoryMetric that surfaced 6 invisible retain cycles, with fixes reducing crash rates by 18% across core chat flows.
• Built Messenger's client performance telemetry using os_signpost with 1-in-100 sampling and Meta Scuba integration, adopted by 3 additional Meta iOS apps after Messenger results.
• Conducted Messenger's first systematic VoiceOver and Dynamic Type accessibility audit, with guidelines adopted by 3 iOS feature teams.

Senior Software Engineer - Reddit, Inc. - San Francisco, CA

(2018-06 - 2019-09)

• Restored feed scroll from 45 - 55fps to smooth 60fps using Texture (AsyncDisplayKit) off-main-thread layout, with XCTest performance tests locking P95 frame time at 16ms and peak scroll memory reduced 25% through lifecycle-aware cell recycling.
• Built an AVPlayer autoplay controller with visibility-based lifecycle, AVAudioSession silent mode respect, and 2-cell pre-buffering that eliminated video load latency on scroll.
• Delivered VoiceOver coverage across all 8 feed cell types with accessibilityCustomActions for vote, save, and share, marking the first accessibility pass in Reddit iOS history.
• Set up Reddit iOS's first Fastlane CI/CD pipeline covering automated build, XCTest, and TestFlight, cutting release prep from around 45 minutes to around 8 minutes per build.

Software Engineer - Snap Inc. - Los Angeles, CA

(2017-10 - 2018-03)

• Eliminated 3 - 5ms of per-frame CPU cost in Snap's live AR lens pipeline by implementing direct zero-copy GPU access via CVMetalTextureCache, keeping 60fps rendering within the 16ms frame budget on iPhone X.
• Built frame latency benchmarking tooling across 5 iPhone tiers, adopted as the camera team's standard pre-release validation workflow for all new lens feature releases.
• Implemented MTLDevice-based device-adaptive quality tiers (Full, Standard, and Lite), delivering reliable 30fps on iPhone 6 and 60fps on iPhone X.

Software Engineer II - Ticketmaster - Los Angeles, CA

(2015-06 - 2017-08)

• Led iOS development of Ticketmaster Verified Fan, a bot-detection and identity-verification flow that protected 10M+ registrations and reduced resale rates from over 30% to under 5% on Harry Styles's 2017 tour.
• Delivered 60fps seat map rendering for 20,000+ seats via CATiledLayer async tile generation and engineered SafeTix HMAC-SHA256 rotating barcodes with 8-second TTL and CoreData offline fallback for stadium dead zones.
• Implemented the team's first VoiceOver and Dynamic Type pass alongside the first Fastlane CI/CD pipeline, cutting App Store release steps from around 45 minutes to around 8 minutes.

B.S. - Computer Science - University of Southern California (USC) (2011-09 - 2015-05)