IOS
317 bites tagged IOS — interview questions with model answers, and 60-second explainers.
Securely managing signing assets in CI/CD
Keep encrypted certificates and profiles in a controlled store or fastlane match repo, inject the decryption key and credentials via CI secrets, install into a temporary keychain per run. secret handling for CI signing.
App Thinning: slicing, bitcode, and on-demand resources
Slicing delivers only the assets and code a device needs; bitcode let Apple recompile and re-optimize; on-demand resources defer large assets until requested. download-size optimization mechanisms.
Automatic signing: benefits and limitations on teams
Automatic signing creates certificates and profiles on demand and keeps them in sync, easing local setup; limits include proliferating certificates, weak CI fit, and less control for complex entitlements. managing signing across a team.
Phased release to limit update risk
Enable phased release so an approved update reaches a growing percentage of automatic-update users over seven days; pause if metrics spike. risk-managed rollout knowledge.
Using dSYM files to symbolicate crash reports
A dSYM maps stripped memory addresses back to function names, files, and line numbers; matched by UUID it symbolicates the report to readable frames. crash symbolication knowledge.
Ad Hoc versus external TestFlight distribution
Ad hoc installs on pre-registered device UDIDs without Apple review; external TestFlight reaches many testers via the app but needs Beta App Review. choosing the right beta channel.
Archiving and uploading a build to TestFlight
Select a real-device or Any iOS destination, Product Archive, then in the Organizer distribute to App Store Connect, where the build appears for internal TestFlight testers after processing. the release-build distribution flow.
App ID, provisioning profile, and signing certificate
The certificate proves who you are, the App ID identifies the app and its capabilities, and the provisioning profile binds certificate, App ID, and allowed devices so iOS trusts the install. the code-signing trust chain.
Developing a local Swift Package alongside an app
Add the package as a local dependency by dragging its folder into the project or workspace, so Xcode references the source on disk and rebuilds edits immediately. local package development workflow.
Static library versus dynamic framework linking
Static code is copied into the executable at build time; dynamic is loaded at launch by dyld. Trade-off: static bloats the binary but avoids load cost; many dynamic frameworks slow launch. linking models and their runtime cost.
Modularizing a monolithic iOS app
Extract low-dependency, high-reuse leaf code first behind clear interfaces, enforce boundaries, iterate inward. incremental modularization strategy.
Package.swift manifest: library vs executable products
The manifest declares name, targets, dependencies, and products; a library is consumed by other code while an executable produces a runnable binary with an entry point. understanding SPM package structure.
Adding a Swift Package dependency in Xcode
Add via File menu, paste the repo URL, choose a version rule like up-to-next-major, link the product to your target. basic SPM workflow knowledge.
Driving app state via launch arguments in XCUITest
Pass launchArguments and launchEnvironment, read them at startup to seed auth and flags, bypassing slow UI steps. setting up test preconditions cheaply.
Diagnosing and stabilizing flaky XCUITests
Identify timing races, animations, network variance, and shared state; fix with expectations, controlled launch state, and isolation. handling nondeterminism in UI automation.
Code coverage and its pitfalls
It measures executed lines, surfaces untested paths, and guides where to add tests. understanding coverage as a signal, not a goal. treating 100 percent as proof of correctness or writing assertion-free tests just to inflate…
Locating XCUITest elements without accessibility identifiers
Query by type, label, predicate, or index; chain queries to narrow scope. navigating the element query hierarchy. relying on brittle absolute indices or visible label text that breaks under localization and layout changes.
Testing async code and completion handlers in XCTest
Create an expectation, fulfill it inside the completion handler, call wait with a timeout, or use async test methods. knowledge of waiting for asynchronous work in tests.
Unit test a ViewModel with a mocked NetworkService
Inject the protocol, supply a mock returning canned data, assert published state transitions. dependency injection and test isolation. hitting the real network or testing the concrete service instead of the ViewModel.
Unit test versus UI test in Xcode
Unit tests (XCTest) exercise code logic in-process and fast; UI tests (XCUITest) drive the app through the accessibility layer, slower and end-to-end. The scope and tooling difference between test types.
Recognize objects in ARKit with a Core ML model
Pull the frame's capturedImage, run Vision/Core ML off the main thread, raycast the 2D detection point into the scene, add an ARAnchor. Combining ARKit, Vision, and Core ML plus 2D-to-3D mapping.
React to location authorization changed in Settings
Implement locationManagerDidChangeAuthorization, which fires on launch and whenever status changes, read authorizationStatus, and start updates when authorized. Observing authorization changes via the delegate.
Apply a CIFilter to a live camera feed
Use AVCaptureSession with AVCaptureVideoDataOutput, receive CMSampleBuffers in captureOutput via the sample buffer delegate on a serial queue, filter with CIImage, drop late frames. Capturing raw frames and the queue discipline.
Display thousands of map annotations efficiently
Enable clustering via clusteringIdentifier, reuse views with dequeueReusableAnnotationView, render clusters with MKClusterAnnotation in viewFor. Annotation clustering and view reuse in MapKit.
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