Initializers and designated init in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a designated initializer for the class.

Swift

class Person {
    var name: String
    init([1]: String) {
        self.name = name
    }
}

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

Ainit

Bself

Cvalue

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'self' or 'init' as parameter names causes errors.

Using a different parameter name without assigning it properly.

The parameter name in the initializer must match the property name to assign it correctly.

2fill in blank

medium

Complete the code to call the designated initializer from a convenience initializer.

Swift

class Vehicle {
    var wheels: Int
    init(wheels: Int) {
        self.wheels = wheels
    }
    convenience init() {
        self.[1](wheels: 4)
    }
}

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Asuper

Bself

Cinit

Dconvenience

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'self' without '.init' causes errors.

Using 'super' in a convenience initializer of the same class.

Convenience initializers call the designated initializer using 'self.init'.

3fill in blank

hard

Fix the error in the initializer by completing the missing keyword.

Swift

class Animal {
    var species: String
    [1] init(species: String) {
        self.species = species
    }
}

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Arequired

Bfinal

Coverride

Dconvenience

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'convenience' instead of 'required' changes initializer type.

Omitting the keyword when subclassing requires it.

The 'required' keyword ensures subclasses implement this initializer.

4fill in blank

hard

Fill both blanks to create a designated initializer with a default parameter value.

Swift

class Book {
    var title: String
    var pages: Int
    init(title: String, pages: [1] = [2]) {
        self.title = title
        self.pages = pages
    }
}

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AInt

B100

CString

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using String type for pages causes type errors.

Omitting the default value or using zero when 100 is expected.

The parameter 'pages' is of type Int with a default value 100.

5fill in blank

hard

Fill all three blanks to complete the subclass initializer calling the superclass designated initializer.

Swift

class Employee: Person {
    var id: Int
    init(name: String, id: [1]) {
        self.id = id
        super.[2](name: [3])
    }
}

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

AString

Binit

Cname

DInt

Attempts:

3 left

💡 Hint

Common Mistakes

Using String type for id causes errors.

Calling 'super' without '.init' is invalid.

Passing wrong argument name to superclass initializer.

The subclass initializer takes an Int id, calls 'super.init' with the name parameter.