Easy everything in iOS & Swift
Rosetta ends for Intel-only Mac apps at macOS 27 as Apple sets a hard deadline
Apple is winding down Rosetta, the translation layer that let Intel-only Mac apps run on Apple silicon since 2020. From macOS 26.4, users launching non-native apps may see an update notification, and macOS 27 is the last release that runs them at all, except older unmaintained games.
Diagnosing choppy scrolling performance
Reach for Instruments, especially the Time Profiler and Core Animation/Hangs tools, and look for main-thread work and dropped frames.
Purpose and setup of an Objective-C bridging header
The bridging header imports ObjC headers into Swift; Xcode auto-creates it or you add it manually and set the build setting.
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.
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.
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.
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.
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.
Play a remote video with AVFoundation
Wrap the URL in AVPlayerItem, feed it to AVPlayer, render with AVPlayerLayer added to the view's layer (or AVPlayerViewController for controls).
Request the user's location one time
Add a usage description to Info.plist, set a CLLocationManager delegate, request when-in-use authorization, call requestLocation, handle didUpdateLocations and didFailWithError.
Add shadow and rounded corners to a UIView
CornerRadius needs masksToBounds true, but that clips the shadow; set shadowPath to keep both and stay performant.
Implicit .animation() vs explicit withAnimation
.animation(value:) animates a view when a tracked value changes; withAnimation wraps the state mutation so all dependent views animate.
Map JSON keys to differently named Codable properties
Declare a nested CodingKeys enum mapping userID to the raw value "user_id", or set the decoder's keyDecodingStrategy to convertFromSnakeCase for blanket conversion.
Fetch and decode JSON with async/await and URLSession
Call URLSession.shared.data(from:) inside an async throws function, check the HTTPURLResponse status, then JSONDecoder().decode([User].self) and let errors propagate via try.
Explain UIKit MVC and the Massive View Controller problem
Model holds data, View displays it, Controller mediates between them; the view controller accretes networking, parsing, and logic into a Massive View Controller.
Describe the iOS app lifecycle and SceneDelegate methods
Not running, inactive, active, background, suspended; SceneDelegate handles sceneDidBecomeActive, sceneWillResignActive, sceneDidEnterBackground, sceneWillEnterForeground.
How does Swift's switch differ from C's switch?
Switches must be exhaustive, there is no implicit fallthrough between cases, and cases can match ranges, tuples, and bind values.
How do you persist a custom Swift struct to JSON in Documents?
Tests fluency with Codable and FileManager sandbox APIs. Good answer: conform to Codable, encode with JSONEncoder, resolve Documents directory via FileManager URLs, write Data atomically, and reverse with JSONDecoder.
When is UserDefaults right, what are its limits, and native types?
Tests if you treat UserDefaults as a small preference store, not a database. Good answers name native plist types, cite no encryption and small size limits, and name Core Data or Keychain for heavy or sensitive data. Red flag: storing images or passwords.
Implement SwiftUI navigation between list and detail with product ID
Tests modern SwiftUI navigation and clean data flow. Great answer: NavigationStack with NavigationLink(value:) and navigationDestination(for:), plus a bound path for programmatic control.
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