Intermediate everything in Mobile Dev, page 7
Track location continuously in the background
Set desiredAccuracy, distanceFilter, activityType; enable the Location background mode and allowsBackgroundLocationUpdates; request Always authorization.
Allow simultaneous pan and pinch gestures
Attach pan and pinch recognizers, set yourself as delegate, return true from shouldRecognizeSimultaneouslyWith, apply translation to center and scale to transform.
Build a custom circular progress bar in UIKit
Draw an arc with UIBezierPath, assign it to a CAShapeLayer path, set lineWidth and no fill, animate strokeEnd 0 to 1.
Difference between frame, bounds, and center
Frame and center are in the superview's space; bounds is the view's own space, usually origin zero. A non-identity transform makes frame undefined to read.
Add a default header to every URLSession request
Set httpAdditionalHeaders on a URLSessionConfiguration, build the session from it, mention per-request overrides win.
What is @MainActor and why does it matter?
@MainActor is a global actor guaranteeing code runs on the main thread; annotate UI-updating types or methods so post-network state changes are main-thread safe.
Run two API calls concurrently with async let
Use async let to start two independent fetches that run concurrently, then await both, so total time approaches the slower call rather than the sum.
URLSession data vs download vs upload tasks
Data tasks buffer responses in memory for small API calls; download tasks stream to a file and support background transfers for large files; upload tasks send bodies from data or files and report…
Why store auth tokens in Keychain, not UserDefaults?
UserDefaults is an unencrypted plist readable from backups and on jailbroken devices; use Keychain Services, which stores encrypted items with access control; save with SecItemAdd and read with…
Test Plans (XCTestPlan)
A Test Plan is an Xcode configuration file decoupling which tests run from how they run, letting one scheme execute many configurations: localizations, sanitizers, randomized order, and repetition, all without editing the scheme.
Dart reduce versus fold on collections
Reduce combines same-type elements and throws on empty; fold takes an initial value and accumulator of any type, safe on empty.
Auth-protected routes via GoRouter redirect
A top-level redirect reads auth state, sends unauthenticated users to login, sends logged-in users away from login, and uses refreshListenable to re-evaluate on auth change.
Isolating and reducing excessive widget rebuilds
Push state down, use const subtrees, rebuild only listeners with ValueListenableBuilder, isolate repaints with RepaintBoundary.
iOS code signing for a TestFlight release
A signing certificate proves who built the app; a provisioning profile ties cert, app ID and devices together; configure in Xcode, archive and upload.
Testing a tap that triggers a SnackBar
PumpWidget the app, find the button, tester.tap it, call pump or pumpAndSettle to advance frames, then expect a SnackBar finder.
MethodChannel data flow and type marshalling
Dart invokeMethod sends a StandardMessageCodec-serialized payload to native, which returns a primitive or map; complex objects must be reduced to supported types.
Per-tab navigation stacks with StatefulShellRoute
StatefulShellRoute keeps a separate Navigator and preserved state per branch, with a shared shell scaffold.
Classic BLoC with Streams and Sinks
Classic BLoC separates UI from business logic by exposing inputs as Sinks and outputs as Streams. The widget pushes events into sinks, the BLoC processes them, and emits new state on streams that the UI rebuilds from, keeping logic testable and…
Android Becomes an Intelligence System: I/O 2026 Recap
Google’s I/O 2026 Android recap introduced AppFunctions experiments, Gemini Nano 4 previews and tools for hybrid AI. Check each feature’s availability and device requirements before using it in production.
Kotlin 2.4.0 Ships Stable Context Parameters and UUID API
Kotlin 2.4.0 ships stable context parameters, a built-in UUID API, and Java 26 support. Context parameters replace manual dependency threading through call chains.
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