Global actors (@MainActor) in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to mark the function as running on the main actor.

Swift

@[1]
func updateUI() {
    print("UI updated")
}

Drag options to blanks, or click blank then click option'

AMainActor

BGlobalActor

CUIActor

DBackgroundActor

Attempts:

3 left

💡 Hint

Common Mistakes

Using @GlobalActor instead of @MainActor

Forgetting the '@' symbol before MainActor

Using unrelated actor names

The @MainActor attribute ensures the function runs on the main thread, which is important for UI updates.

2fill in blank

medium

Complete the code to declare a global actor named MyActor.

Swift

@globalActor
struct [1] {
    static let shared = MyActor()
}

Drag options to blanks, or click blank then click option'

AYourActor

BGlobalActor

CMainActor

DMyActor

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different name than the shared instance

Confusing with built-in actors like MainActor

The struct name must match the global actor name, here 'MyActor'.

3fill in blank

hard

Fix the error in the code to ensure the function runs on the main actor.

Swift

[1]
func updateData() async {
    print("Data updated")
}

Drag options to blanks, or click blank then click option'

A@MainActor

Basync

C@globalActor

D@UIActor

Attempts:

3 left

💡 Hint

Common Mistakes

Using @globalActor which is not a valid attribute

Placing async incorrectly

Using a non-existent actor like @UIActor

Adding @MainActor before the function ensures it runs on the main actor.

4fill in blank

hard

Fill both blanks to declare a global actor and use it on a function.

Swift

@globalActor
struct [1] {
    static let shared = [1]()
}

@[2]
func performTask() {
    print("Task performed")
}

Drag options to blanks, or click blank then click option'

ACustomActor

BMainActor

DGlobalActor

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for struct and shared instance

Using @MainActor instead of the custom actor

The struct name and shared instance must match, and the function uses the declared global actor attribute.

5fill in blank

hard

Fill all three blanks to create a global actor, mark a class with it, and declare an async function.

Swift

@globalActor
struct [1] {
    static let shared = [1]()
}

[2]
class DataManager {
    func fetchData() [3] {
        print("Fetching data")
    }
}

Drag options to blanks, or click blank then click option'

ANetworkActor

C@NetworkActor

Dasync

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting '@' before the actor name on the class

Mismatching struct and shared instance names

Omitting async keyword on the function

The struct and shared instance names must match, the class is marked with the global actor attribute, and the function is async.