Labeled statements for nested loops in Swift - Step-by-Step Execution

Concept Flow - Labeled statements for nested loops

Start Outer Loop

↓

Start Inner Loop

↓

Check Condition

↓

Action

↓

Check Break?

↓

Break Outer Loop

↓

End

The outer loop runs, inside it the inner loop runs. A labeled break can exit the outer loop from inside the inner loop.

Execution Sample

Swift

outerLoop: for i in 1...3 {
    for j in 1...3 {
        if i * j == 4 {
            break outerLoop
        }
        print("i=\(i), j=\(j)")
    }
}

This code runs two loops. When i*j equals 4, it breaks out of the outer loop entirely.

Execution Table

Step	i	j	Condition i*j==4	Action	Output
1	1	1	1*1=1 (False)	Print i=1, j=1	i=1, j=1
2	1	2	1*2=2 (False)	Print i=1, j=2	i=1, j=2
3	1	3	1*3=3 (False)	Print i=1, j=3	i=1, j=3
4	2	1	2*1=2 (False)	Print i=2, j=1	i=2, j=1
5	2	2	2*2=4 (True)	Break outerLoop
6	-	-	-	Exit all loops

💡 At step 5, condition i*j==4 is true, so break outerLoop exits both loops.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	Final
i	-	1	1	1	2	2	-
j	-	1	2	3	1	2	-

Key Moments - 3 Insights

Why does the break statement exit the outer loop and not just the inner loop?

Because the break uses the label 'outerLoop', it tells Swift to exit that specific loop, not just the inner one. See execution_table step 5 where break outerLoop happens.

What happens if the condition i*j==4 never becomes true?

The inner loop finishes all iterations for each i, and the outer loop continues normally. No labeled break occurs, so loops run fully.

Why is there no output after step 5?

Because the break outerLoop stops all loops immediately, so no further print statements run after step 5.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of j at step 4?

A 3

B 1

C 2

D -

💡 Hint

Check the 'j' column in execution_table row for step 4.

At which step does the condition i*j==4 become true?

A Step 5

B Step 3

C Step 4

D Step 6

💡 Hint

Look at the 'Condition i*j==4' column in execution_table.

If we remove the label and just write 'break', what happens when i*j==4?

A Causes a compile error

B Breaks both loops

C Breaks only inner loop and continues outer loop

D Skips current iteration

💡 Hint

Recall that unlabeled break exits the nearest loop only.

Concept Snapshot

Labeled statements let you name loops.
Use 'break label' to exit that loop from inside nested loops.
Syntax: labelName: for ... { ... break labelName ... }
Without label, break exits nearest loop only.
Useful to stop multiple loops at once.

Full Transcript

This visual trace shows how labeled statements work in nested loops in Swift. The outer loop runs from 1 to 3, and inside it the inner loop runs from 1 to 3. At each step, the product i*j is checked. When it equals 4, the break with label 'outerLoop' stops both loops immediately. The execution table shows each step's variables and actions. The variable tracker shows how i and j change. Key moments clarify why the labeled break exits the outer loop, what happens if the condition never triggers, and why no output appears after the break. The quiz tests understanding of variable values at steps, when the condition triggers, and the effect of removing the label. The snapshot summarizes how to use labeled breaks to control nested loops in Swift.