Calling super for parent behavior in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the super keyword do in Swift?

<p>The <code>super</code> keyword calls a method or property from the parent class. It lets a child class use or extend the behavior of its parent.</p>

beginner

Why should you call super when overriding a method?

Calling super ensures the parent class's original behavior runs. This keeps important setup or logic intact while adding new behavior.

beginner

Example: How to call super.viewDidLoad() in a UIViewController subclass?

override func viewDidLoad() {
    super.viewDidLoad()
    // Your code here
}

This calls the parent viewDidLoad() to keep default setup.

intermediate

What happens if you forget to call super in an overridden initializer?

Not calling super.init() can cause your object to be incomplete or crash because the parent class's setup is skipped.

intermediate

Can you call super in a method that is not overridden?

No. You can only call super inside a method that overrides a parent method. Otherwise, the compiler will give an error.

What is the purpose of calling super.method() in Swift?

A To create a new method in the child class

B To run the parent class's version of the method

C To delete the parent class's method

D To call a method from an unrelated class

Calling super.method() runs the parent class's method, preserving its behavior.

What happens if you override viewDidLoad() in a UIViewController subclass but do NOT call super.viewDidLoad()?

A The app will crash immediately

B The method will call itself recursively

C Nothing, it works fine without calling super

D The parent setup code will not run, possibly causing issues

Not calling super.viewDidLoad() skips important setup done by the parent, which can cause unexpected behavior.

Can you call super in a method that does not override a parent method?

A No, only in overridden methods

B Yes, anytime

C Only in initializers

D Only in static methods

You can only call super inside methods that override a parent method.

When overriding an initializer in Swift, what must you do to ensure proper setup?

A Call <code>super.init()</code> to run the parent initializer

B Call <code>self.init()</code> instead

C Do nothing special

D Call <code>super.deinit()</code>

Calling super.init() runs the parent class's initializer to set up inherited properties.

What keyword do you use to access the parent class's method in Swift?

A parent

B base

C super

D self

The keyword super accesses the parent class's methods and properties.

Explain why and how you use super when overriding methods in Swift.

Think about keeping the parent's work while adding your own.

Describe what can go wrong if you forget to call super.init() in a subclass initializer.

Consider what the parent class normally does in its initializer.