Cancellation handling in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a task has been cancelled.

Swift

if Task.isCancelled [1] {
    print("Task was cancelled")
}

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

Ais

B== false

C!=

D== true

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' false instead of '== true'

Using 'is' keyword incorrectly

Omitting the comparison operator

The property Task.isCancelled returns true if the task was cancelled. So we check if it is true.

2fill in blank

medium

Complete the code to throw a cancellation error inside an async task.

Swift

func fetchData() async throws {
    guard !Task.[1] else {
        throw CancellationError()
    }
    // continue fetching data
}

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

AisCancelled

Bcancelled

Ccancel

DisCanceling

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect property names like 'cancelled' or 'cancel'

Using 'isCanceling' which does not exist

The property Task.isCancelled is used to check if the current task has been cancelled.

3fill in blank

hard

Fix the error in the code to properly handle cancellation inside a Task.

Swift

Task {
    try await someAsyncFunction()
    if [1] {
        print("Cancelled")
    }
}

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

Aself.cancelled

BTask.cancelled

CTask.isCancelled

Dself.isCancelled

Attempts:

3 left

💡 Hint

Common Mistakes

Using instance properties instead of the static property

Using incorrect property names

Inside a Task, use Task.isCancelled to check if the task was cancelled.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that includes only non-cancelled tasks.

Swift

let activeTasks = [task: status for (task, status) in allTasks if task.[1] == false && !Task.[2]]

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

AisCancelled

Bcancelled

Dcanceling

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'cancelled' or 'canceling' which are not valid properties

Mixing instance and static properties incorrectly

Check each task's isCancelled property and also the static Task.isCancelled to filter out cancelled tasks.

5fill in blank

hard

Fill all three blanks to create a dictionary of task names and statuses for tasks that are not cancelled.

Swift

let filteredTasks = [[1]: [2] for ([3], status) in tasks if ![3].isCancelled]

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

Atask.name

Bstatus

Ctask

Dtasks

Attempts:

3 left

💡 Hint

Common Mistakes

Using the whole task as key instead of task.name

Using wrong variable names in the loop

The dictionary uses task.name as keys and status as values, iterating over task in tasks.