Error protocol conformance in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an error type conforming to the Error protocol.

Swift

enum NetworkError: [1] {
    case badURL
    case timeout
}

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

AError

BEquatable

CCodable

DCustomStringConvertible

Attempts:

3 left

💡 Hint

Common Mistakes

Using protocols like Equatable or Codable instead of Error.

Forgetting to conform to any protocol.

In Swift, to create a custom error type, you declare an enum that conforms to the Error protocol.

2fill in blank

medium

Complete the code to throw a custom error conforming to Error protocol.

Swift

func fetchData(from url: String) throws {
    guard url.hasPrefix("http") else {
        throw [1].badURL
    }
}

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AError

BString

CNSError

DNetworkError

Attempts:

3 left

💡 Hint

Common Mistakes

Throwing a protocol name like Error instead of a concrete error case.

Throwing a String or NSError directly.

You throw an instance of your custom error type, here NetworkError.badURL.

3fill in blank

hard

Fix the error in the code to properly conform to the Error protocol.

Swift

struct FileError: [1] {
    let message: String
}

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ACodable

BEquatable

CError

DCustomStringConvertible

Attempts:

3 left

💡 Hint

Common Mistakes

Using other protocols instead of Error.

Not conforming to any protocol.

To make FileError an error type, it must conform to the Error protocol.

4fill in blank

hard

Fill both blanks to define and throw a custom error conforming to Error protocol.

Swift

enum [1]: [2] {
    case invalidInput
}

func validate(input: String) throws {
    if input.isEmpty {
        throw [1].invalidInput
    }
}

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AValidationError

BError

CString

DCustomError

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatching enum name in throw statement.

Not conforming enum to Error protocol.

The enum ValidationError conforms to Error and is used to throw invalidInput error.

5fill in blank

hard

Fill all three blanks to create a custom error with a localized description.

Swift

struct [1]: [2] {
    var localizedDescription: String {
        return [3]
    }
}

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ACustomError

BError

C"An error occurred"

D"Error"

Attempts:

3 left

💡 Hint

Common Mistakes

Not conforming to Error protocol.

Returning a non-string value in localizedDescription.

CustomError conforms to Error and provides a localizedDescription string.