URLSession basics in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a default URLSession instance.

iOS Swift

let session = URLSession.[1]

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Adefault

Bshared

Cconfiguration

Dinit

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'default()' which does not exist

Trying to call 'init()' directly

The shared property gives you a shared singleton URLSession instance for simple tasks.

2fill in blank

medium

Complete the code to create a URL from a string.

iOS Swift

guard let url = URL(string: [1]) else { return }

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A"https://apple.com"

BURL(string: "https://apple.com")

CurlString

Dhttps://apple.com

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a URL object instead of a string

Forgetting quotes around the URL string

The URL(string:) initializer expects a string literal or variable containing the URL string.

3fill in blank

hard

Fix the error in the code to start a data task.

iOS Swift

let task = session.dataTask(with: url) [1]

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A.begin()

B.start()

C.resume()

D.run()

Attempts:

3 left

💡 Hint

Common Mistakes

Using .start() or .begin() which are not valid methods

Forgetting to call any method to start the task

You must call resume() on the task to start it. Other methods do not exist.

4fill in blank

hard

Fill both blanks to handle the data and error in the completion handler.

iOS Swift

let task = session.dataTask(with: url) { data, response, [1] in
    if let error = [2] {
        print(error.localizedDescription)
    }
}

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Aerror

Berr

Cfailure

Dexception

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the parameter and the unwrapped variable

Using undefined variable names

The completion handler parameter for errors is usually named error. You check it with if let error = error.

5fill in blank

hard

Fill all three blanks to safely unwrap data and convert it to a string.

iOS Swift

let task = session.dataTask(with: url) { data, response, error in
    guard let [1] = data, error == nil else { return }
    let result = String(data: [2], encoding: [3])
    print(result ?? "No data")
}

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Adata

Bresponse

CString.Encoding.utf8

DString.Encoding.ascii

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'response' instead of 'data'

Using ASCII encoding which may not work for all data

You unwrap data safely, then use it to create a string with UTF-8 encoding.