(Mobile Dev) Flashcards

Which Swift property wrapper automatically publishes changes to SwiftUI views in Combine-based code?

Answer: @Published

@Published marks a property so that changes automatically broadcast through Combine's ObservableObject protocol.

What is the purpose of `@escaping` in a Swift closure parameter?

Answer: It allows the closure to outlive the function call

@escaping tells the compiler the closure may be stored or called after the enclosing function returns.

In UIKit, which method must you call to ensure UI updates happen on the correct thread?

Answer: DispatchQueue.main.async

UIKit is not thread-safe, so all UI mutations must be dispatched to DispatchQueue.main.

Which Swift concurrency keyword suspends execution until an async function returns a result?

Answer: await

`await` pauses the current async context until the called async function produces its result.

What does the `lazy` keyword do when applied to a stored property in Swift?

Answer: Delays initialization until first access

A `lazy` stored property's initializer runs only when the property is first accessed, not at instance creation.

In SwiftUI, which modifier correctly passes a two-way binding into a child view?

Answer: $variable

Prefixing a @State or @StateObject variable with `$` produces a Binding for two-way data flow.

Which Foundation class is most appropriate for making HTTP network requests in Swift without third-party libraries?

Answer: URLSession

URLSession is Apple's built-in API for performing HTTP/HTTPS data tasks, uploads, and downloads.