Delegates enable objects to communicate events and customize behavior. The delegate pattern uses protocols to define a contract—I create a protocol with optional and required methods, and the delegating object holds a weak reference to avoid retain cy

Ruby's metaprogramming enables dynamic method definition and interception. method_missing catches undefined method calls, allowing DSL creation and proxy patterns. I implement it carefully with respond_to_missing? for proper introspection. define_meth

Sign in with Apple provides secure, privacy-focused authentication required for apps with third-party login. Users create accounts with Face ID or Touch ID, and Apple generates unique identifiers per app. I use ASAuthorizationController to initiate th

Linux system administration is fundamental to DevOps. Process management with ps, top, htop monitors system activity. systemctl manages systemd services—start, stop, enable, disable. Disk management with df, du, lsblk, mount handles storage. journalct

Services run background operations without UI. I extend Service and override onStartCommand() for started services or onBind() for bound services. Foreground services use startForeground() with ongoing notification, required for long-running tasks vis

AVFoundation provides comprehensive audio and video capabilities. AVPlayer plays media from URLs or local files with playback controls. AVPlayerLayer renders video content in views. I observe player state with KVO or Combine to track playback progress

Spring WebFlux enables reactive, non-blocking applications using Project Reactor. Mono represents 0-1 elements, Flux represents 0-N elements. Reactive programming handles high concurrency with fewer threads. I use reactive repositories with R2DBC for

SLF4J provides a logging facade, Logback implements it efficiently. I use logger levels—TRACE, DEBUG, INFO, WARN, ERROR—to control verbosity. Parameterized logging with {} placeholders improves performance versus string concatenation. MDC (Mapped Diag

PostgreSQL JSONB stores binary JSON efficiently with indexing support. I use JSONB for semi-structured data, dynamic attributes, event logs. JSONB operators enable querying nested data—->, ->>, @>, ?. GIN indexes accelerate JSONB queries.

Evaluation goes wrong when data splitting is treated like boilerplate. I stratify imbalanced targets, guard time order when necessary, and make sure preprocessing lives inside cross-validation. This is the difference between a model that looks good in

When the search space is wide, Optuna gives me better signal per compute dollar than brute-force sweeps. It is easy to define conditional search spaces, prune bad trials early, and track the best trial artifacts. I especially like it for gradient boos

I like spaCy for production NLP because it balances performance, ergonomics, and deployability. It is especially good for entity extraction, rule-based matching, and clean token-level processing. I often pair learned models with explicit match pattern