Swift Technology & Digital Applications 5

Question 1

What does Swift's `Sendable` protocol communicate about a type?

Accepted Answer

The type is safe to pass across actor boundaries without data races

Answer

`Sendable` marks types whose values can be safely shared across concurrency domains (actors or tasks) because they don't allow shared mutable state.

Question 2

In Swift, what is the difference between `map` and `compactMap` on a sequence?

Accepted Answer

`compactMap` transforms elements and removes nil results; `map` keeps all results

Answer

`compactMap` applies a transform that returns an optional and automatically filters out `nil` results, whereas `map` preserves every transformed element.

Question 3

Which Swift access control level restricts a declaration to the file in which it is defined?

Accepted Answer

fileprivate

Answer

`fileprivate` limits access to the defining source file, unlike `private` which restricts to the enclosing declaration and its extensions in the same file.

Question 4

What is an `actor` in Swift Concurrency?

Accepted Answer

A reference type that protects its mutable state from concurrent access

Answer

An `actor` is a reference type that serializes access to its mutable state, preventing data races without explicit locking.

Question 5

Which SwiftUI property wrapper is appropriate for a view that owns and manages an `ObservableObject` instance?

Accepted Answer

@StateObject

Answer

`@StateObject` creates and owns the object's lifetime tied to the view, preventing unnecessary re-creation across re-renders.

Swift Practice Test

Swift Practice Test

Swift Technology & Digital Applications 5