Calling super for parent behavior in Swift - Step-by-Step Execution

Concept Flow - Calling super for parent behavior

Child method called

↓

Child method runs custom code

↓

Call super.method()

↓

Parent method runs

↓

Return to child method

↓

Child method finishes

When a child class method runs, it can do its own work and then call the parent class method using super to keep the parent's behavior.

Execution Sample

Swift

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

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

let c = Child()
c.greet()

This code shows a child class method calling super to run the parent class method after its own code.

Execution Table

Step	Action	Output	Notes
1	Create Child instance c		Child object created
2	Call c.greet()		Child's greet() method starts
3	Print "Hello from Child"	Hello from Child	Child prints its message
4	Call super.greet()		Parent's greet() method called
5	Print "Hello from Parent"	Hello from Parent	Parent prints its message
6	Return from super.greet()		Back to Child's greet()
7	Child's greet() finishes		Method ends

💡 Child's greet() method finishes after calling parent's greet() via super

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 7
c	nil	Child instance created	Child instance exists	Child instance exists

Key Moments - 2 Insights

Why do we call super.greet() inside the child's greet() method?

Calling super.greet() runs the parent class's greet() method so the child keeps the parent's behavior in addition to its own, as shown in steps 4 and 5.

What happens if we don't call super.greet() in the child's greet()?

If super.greet() is not called, the parent's greet() method won't run, so only the child's message prints. This is seen by comparing step 5's absence.

Visual Quiz - 3 Questions

Look at the execution table, what is printed at step 3?

A Nothing is printed

B "Hello from Parent"

C "Hello from Child"

D "Hello from Child" and "Hello from Parent"

💡 Hint

Check the Output column at step 3 in the execution_table

At which step does the parent's greet() method run?

A Step 4

B Step 5

C Step 2

D Step 7

💡 Hint

Look for the step where "Hello from Parent" is printed in the execution_table

If we remove super.greet() from the child's greet(), what changes in the output?

A Only "Hello from Child" prints

B Only "Hello from Parent" prints

C Both messages print as before

D No messages print

💡 Hint

Refer to key_moments explanation about skipping super.greet()

Concept Snapshot

Calling super.method() lets a child class run the parent class's method.
Use it inside an overridden method to keep parent behavior.
Without super, parent's code is skipped.
Example: override func greet() { print("Child"); super.greet() }

Full Transcript

This example shows how a child class method can run its own code and then call the parent class method using super. When c.greet() is called, the child prints "Hello from Child", then calls super.greet() which prints "Hello from Parent". This keeps both behaviors. If super.greet() is omitted, only the child's message prints. The execution table traces each step, showing when each print happens and how the method calls flow.