Switch statement power in Swift - Step-by-Step Execution

Concept Flow - Switch statement power

Start with a value

↓

Evaluate switch expression

↓

Check case 1

No→Check case 2

↓

Execute case 1

↓

Exit switch

The switch statement checks a value against multiple cases and runs the matching case's code, or the default if none match.

Execution Sample

Swift

let number = 3
switch number {
case 1:
    print("One")
case 2, 3:
    print("Two or Three")
default:
    print("Other")
}

This code checks the number and prints a message depending on its value.

Execution Table

Step	Switch Expression	Case Checked	Match?	Action	Output
1	3	case 1	No	Skip
2	3	case 2, 3	Yes	Execute print	Two or Three
3	3	default	Skipped	Exit switch

💡 Matched case 2, 3; executed print and exited switch

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
number	3	3	3	3

Key Moments - 2 Insights

Why does the switch stop after matching case 2, 3 and not check default?

In Swift, once a case matches and executes, the switch exits automatically (see execution_table step 3). No fall-through happens unless explicitly stated.

Can a case check multiple values like case 2, 3?

Yes, Swift allows multiple values in one case separated by commas, so case 2, 3 matches if the value is 2 or 3 (see execution_table step 2).

Visual Quiz - 3 Questions

Look at the execution table, what is the output at step 2?

A "Two or Three"

B "One"

C "Other"

D No output

💡 Hint

Check the 'Output' column at step 2 in the execution_table.

At which step does the switch statement stop checking cases?

A Step 1

B Step 2

C Step 3

D It checks all cases

💡 Hint

Look at the 'Match?' and 'Action' columns in execution_table to see when it stops.

If number was 5, what would be the output?

A "One"

B "Two or Three"

C "Other"

D No output

💡 Hint

Refer to the default case in the code and execution_table logic.

Concept Snapshot

switch value {
 case val1:
   // code
 case val2, val3:
   // code
 default:
   // code
}
- Checks value against cases
- Runs matching case code
- Exits after first match
- Default runs if no match

Full Transcript

This visual execution shows how a Swift switch statement works. It starts by evaluating the value to check. Then it compares this value to each case in order. If a case matches, it runs that case's code and stops checking further cases. If no case matches, it runs the default case. In the example, the number 3 matches the case with 2 and 3, so it prints "Two or Three" and exits. Variables remain unchanged during this process. This helps beginners see exactly how switch chooses which code to run.