Calling super for parent behavior in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Swift code using super?

Consider the following Swift classes. What will be printed when Child().greet() is called?

Swift

class Parent {
    func greet() {
        print("Hello from Parent")
    }
}

class Child: Parent {
    override func greet() {
        super.greet()
        print("Hello from Child")
    }
}

Child().greet()

A Hello from Child\nHello from Parent

B Hello from Child

C Hello from Parent\nHello from Child

D Hello from Parent

💡 Hint

Remember that super.greet() calls the parent class method first.

The Child class overrides greet() and calls super.greet() first, which prints "Hello from Parent". Then it prints "Hello from Child".

🧠 Conceptual

intermediate

Why use super in Swift class methods?

Which of the following best explains why you would call super.method() inside an overridden method?

A To prevent the parent class method from running.

B To call the parent class's implementation and add extra behavior in the child class.

C To call a method from a sibling class.

D To create a new method unrelated to the parent.

💡 Hint

Think about how inheritance works and extending behavior.

Calling super.method() lets the child class reuse the parent class's code and then add or change behavior.

🔧 Debug

advanced

What error occurs when calling super in a Swift initializer incorrectly?

Examine this Swift code snippet. What error will it produce?

Swift

class Parent {
    init() {
        print("Parent init")
    }
}

class Child: Parent {
    override init() {
        print(self)
        super.init()
    }
}

A Error: Cannot override initializer in subclass

B No error, prints 'Child init' then 'Parent init'

C Error: Missing required initializer

D Error: 'super.init()' must be called before accessing self or properties

💡 Hint

Swift requires calling super.init() before using self in initializers.

In Swift, you must call super.init() before accessing self or its properties in an initializer. Printing before calling super.init() accesses self, causing an error.

📝 Syntax

advanced

Which option correctly calls the parent method in Swift?

Which of the following is the correct way to call a parent class method named display() inside an overridden method?

A super.display()

B Parent.display()

C self.super.display()

D super->display()

💡 Hint

Remember the Swift syntax for calling parent methods.

In Swift, super.methodName() calls the parent class's method. Other options are invalid syntax.

🚀 Application

expert

What is the final value of count after calling increment() twice?

Given these Swift classes, what is the value of count after Child().increment() is called twice?

Swift

class Parent {
    var count = 0
    func increment() {
        count += 1
    }
}

class Child: Parent {
    override func increment() {
        super.increment()
        count += 2
    }
}

let obj = Child()
obj.increment()
obj.increment()
print(obj.count)

A 6

B 4

C 2

D 8

💡 Hint

Each call adds 1 from super.increment() and 2 more in Child.increment().

Each increment() call adds 3 to count (1 from parent, 2 from child). Two calls add 6 total.