Swift (Mobile Dev) 2

Question 1

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

Accepted Answer

@Published

Answer

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

Question 2

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

Accepted Answer

It allows the closure to outlive the function call

Answer

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

Question 3

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

Accepted Answer

DispatchQueue.main.async

Answer

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

Question 4

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

Accepted Answer

await

Answer

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

Question 5

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

Accepted Answer

Delays initialization until first access

Answer

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

Swift Practice Test