Senior iOS & macOS engineer, SDKs, mobile security, on-device AI. Vancouver, BC.
I build the layers apps depend on but rarely write themselves: credential storage, binary and runtime integrity, on-device inference, and the SDK surfaces that make all of it a two-line integration. Twelve years in Swift and Objective-C, currently founder and lead engineer at Sentinel Den.
- Security SDKs at parity across platforms: twelve production SDKs, Swift and Kotlin, one protocol surface and one typed error model, shipped as code-signed binaries.
- On-device AI under a privacy constraint: PII redaction across image, audio and text with compute routed between the Neural Engine, GPU and an INT4 CPU kernel. Nothing leaves the device.
- LLM agent containment: sandboxing agents behind a typed tool registry, and measuring what actually gets through.
- Binary analysis & release integrity: Mach-O, APK and DEX inspection, code signing, notarization, App Attest, TLS pinning with rotation.
| Project | What it does |
|---|---|
| xcprivacy-lint | Validates PrivacyInfo.xcprivacy against the APIs your binary actually calls. Catches App Store privacy-manifest rejections before submission, not after. Swift, MIT. |
| machoscope | Mach-O hardening inspector, PIE, stack canaries, runpath safety, code signing. Says when a finding is inferred rather than observed. Swift, MIT. |
| agent-injection-bench | An open benchmark for prompt injection against tool-calling agents, published with its dataset. Deterministic scoring, no judge model. Python, MIT. |
| framework-size-report | Measures what a framework actually costs an app, diffs it per pull request, and fails the build past budget. Swift, MIT. |
| swift6-migration-notes | Swift 6 strict-concurrency migration cases from migrating twelve SDKs. Every fix compiles under Swift 6 mode, so none of it goes stale. |
| sentinelctl-action | Audits an iOS or Android build in CI. Findings land in the GitHub Security tab as SARIF. |
Long-form engineering posts and published root-cause analyses at sentinelden.com/blog: the debugging writeups I wish I'd found while I was stuck.
Swift 6 · Objective-C · Kotlin · TypeScript · Dart · C/C++ · Python
SwiftUI · UIKit · AppKit · Swift Concurrency · Combine · Core Data · iOS / macOS / visionOS · CryptoKit · Secure Enclave · App Attest · React Native · Flutter · Cloudflare Workers · XCTest / XCUITest · Fastlane · GitHub Actions
LinkedIn · sentinelden.com · imkjunejo@gmail.com
Open to senior and staff iOS / macOS roles across Canada, and to remote.