Extension syntax in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an extension for the String type.

Swift

extension String [1] {
    func greet() {
        print("Hello, \(self)!")
    }
}

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

A(

B{

C[

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or brackets instead of curly braces for the extension body.

In Swift, extensions are declared using the 'extension' keyword followed by the type name and then a pair of curly braces '{ }' to contain the new methods or properties.

2fill in blank

medium

Complete the code to add a computed property 'isLong' to String that returns true if the string length is greater than 10.

Swift

extension String {
    var isLong: Bool [1] {
        return self.count > 10
    }
}

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

Aget()

Bset

Cget

Dset()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'set' instead of 'get' for a read-only computed property.

Adding parentheses after 'get'.

Computed properties in Swift use 'get' to define the getter block without parentheses.

3fill in blank

hard

Fix the error in the extension by completing the method signature correctly.

Swift

extension Int {
    func squared() -> Int [1] {
        return self * self
    }
}

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

A{

B(

C[

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or brackets instead of curly braces after the method signature.

Function bodies in Swift are enclosed in curly braces '{ }'. The method signature must be followed by '{' to start the body.

4fill in blank

hard

Fill both blanks to add a mutating method 'increment' to Int that increases its value by 1.

Swift

extension Int {
    mutating func increment() [1] [2] self += 1
}

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

A{

B}

C-> Void

Din

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting curly braces or using '-> Void' incorrectly.

Using 'in' which is for closures, not method bodies.

Mutating methods in Swift structs must have their body enclosed in curly braces '{' and '}'. The '-> Void' is optional and 'in' is used in closures, not here.

5fill in blank

hard

Fill all three blanks to add a static method 'description' to Double that returns a string describing the type.

Swift

extension Double {
    static func description() [1] String [2] {
        return "Double type"
    [3]

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

A->

B{

C}

Din

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the return arrow '->'.

Misplacing or missing curly braces.

Using 'in' which is for closures.

Function return types are indicated with '->'. The method body starts with '{' and ends with '}'. 'in' is not used here.