Switch with value binding in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to bind the value in the switch case.

Swift

let point = (3, 4)
switch point {
case (let [1], 4):
    print("x is \([1])")
default:
    break
}

Drag options to blanks, or click blank then click option'

Ax

By

Cvalue

Dz

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name that doesn't match the print statement.

Forgetting to use 'let' before the variable name.

The 'let x' binds the first element of the tuple to the variable x, which is then used in the print statement.

2fill in blank

medium

Complete the code to bind the associated value in the enum switch.

Swift

enum Result {
    case success(Int)
    case failure(String)
}

let result = Result.success(10)
switch result {
case .success(let [1]):
    print("Success with value \([1])")
case .failure(let message):
    print("Failure: \(message)")
}

Drag options to blanks, or click blank then click option'

Aerror

Bvalue

Cresult

Dnumber

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name that is not used in the print statement.

Not using 'let' to bind the associated value.

The 'let value' binds the associated Int value from the success case, which is then printed.

3fill in blank

hard

Fix the error in the switch statement by correctly binding the tuple values.

Swift

let coordinate = (x: 5, y: 0)
switch coordinate {
case ([1], 0):
    print("On the x-axis at \([1])")
default:
    print("Not on the x-axis")
}

Drag options to blanks, or click blank then click option'

Alet x

Bx

Clet y

Dy

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting 'let' before the variable name.

Using the wrong variable name that doesn't match the print statement.

Using 'let x' correctly binds the first element of the tuple to x, which is then used in the print statement.

4fill in blank

hard

Fill both blanks to bind the tuple values and print them.

Swift

let point = (2, 3)
switch point {
case ([1], [2]):
    print("x is \([1]), y is \([2])")
}

Drag options to blanks, or click blank then click option'

Alet x

Blet y

Cx

Dy

Attempts:

3 left

💡 Hint

Common Mistakes

Not using 'let' before variable names.

Using variable names that don't match the print statement.

Both 'let x' and 'let y' bind the tuple elements to variables x and y, which are then used in the print statement.

5fill in blank

hard

Fill all three blanks to bind values in the enum with associated values and print them.

Swift

enum Message {
    case text(String, Int)
    case image(String)
}

let message = Message.text("Hello", 5)
switch message {
case .text([1], [2]):
    print("Text: \([1]), count: \([2])")
case .image(let name):
    print("Image named \(name)")
}

Drag options to blanks, or click blank then click option'

Alet text

Blet count

Ccount

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'let' inside the parentheses when it's not needed.

Mismatching variable names with the print statement.

The variables 'text' and 'count' are bound without 'let' inside the case pattern, and are used in the print statement.

Practice

1. What does value binding in a switch statement allow you to do in Swift?

easy

A. Capture parts of the matched value for use inside the case block

B. Change the type of the value being switched on

C. Skip checking the value and run all cases

D. Automatically loop through all possible values

Solution

1. Step 1: Understand value binding concept

   Value binding lets you take a part of the value matched in a case and give it a name to use inside that case.

2. Step 2: Recognize its purpose in switch

   This helps you work with the matched data directly without extra code.

3. Final Answer:

   Capture parts of the matched value for use inside the case block -> Option A

4. Quick Check:

   Value binding = capture matched value parts [OK]

Hint: Value binding captures matched data for use inside cases [OK]

Common Mistakes:

• Thinking it changes the value type
• Believing it skips cases
• Assuming it loops automatically

2. Which of the following is the correct syntax for value binding in a Swift switch case?

easy

A. case x let:

B. case let x:

C. case let:

D. case var:

Solution

1. Step 1: Recall correct value binding syntax

   In Swift, value binding uses let or var before a variable name in the case pattern, like case let x:.

2. Step 2: Check options for correct order

   Only case let x: uses let followed by a variable name correctly.

3. Final Answer:

   case let x: -> Option B

4. Quick Check:

   Correct syntax = case let variable: [OK]

Hint: Remember: 'case let variable:' is the right order [OK]

Common Mistakes:

• Placing variable before let
• Omitting variable name
• Using let without variable

3. What will be the output of this Swift code?

let point = (3, 0)
switch point {
 case let (x, 0):
     print("On the x-axis at \(x)")
 case let (0, y):
     print("On the y-axis at \(y)")
 default:
     print("Somewhere else")
}

medium

A. On the x-axis at 3

B. On the y-axis at 0

C. Somewhere else

D. Syntax error

Solution

1. Step 1: Match the tuple with cases

   The tuple is (3, 0). The first case matches any tuple where the second value is 0, binding the first to x.

2. Step 2: Execute matching case

   Since (3, 0) matches case let (x, 0):, it prints "On the x-axis at 3".

3. Final Answer:

   On the x-axis at 3 -> Option A

4. Quick Check:

   Tuple (3,0) matches x-axis case [OK]

Hint: Check tuple pattern carefully to find matching case [OK]

Common Mistakes:

• Confusing x and y positions
• Choosing default case incorrectly
• Assuming syntax error

4. Identify the error in this Swift switch statement using value binding:

let number = 5
switch number {
 case let x where x > 0:
     print("Positive")
 case let x where x < 0:
     print("Negative")
 case x == 0:
     print("Zero")
}

medium

A. Missing 'let' keyword in the last case

B. Incorrect use of 'where' in first two cases

C. Invalid pattern syntax in the last case

D. Switch statement missing default case

Solution

1. Step 1: Review last case syntax

   The last case uses case x == 0:, which is not valid pattern syntax in Swift.

2. Step 2: Correct pattern usage

   It should use value binding with a where clause, like case let x where x == 0:.

3. Final Answer:

   Invalid pattern syntax in the last case -> Option C

4. Quick Check:

   Pattern must be 'case let x where condition' [OK]

Hint: Use 'case let x where condition' for conditions [OK]

Common Mistakes:

• Writing conditions directly after case without let
• Omitting where keyword
• Assuming default case is mandatory

5. Given an array of optional integers, how can you use a switch with value binding to print only the non-nil values?

let numbers: [Int?] = [3, nil, 7, nil, 1]
for number in numbers {
    switch number {
    case let x:
        print(x)
    case nil:
        print("No value")
    }
}

What is the problem and how to fix it?

hard

A. The order of cases is wrong; put 'case nil' before 'case let x' to match nil first

B. Add a default case to handle nil values

C. Replace 'case let x' with 'case let x!' to unwrap optionals

D. Use 'case let x?' to bind only non-nil values, and 'case nil' for nil

Solution

1. Step 1: Understand optional pattern matching

   Using case let x: matches all values including nil, so case nil: is never reached.

2. Step 2: Use optional pattern binding

   Use case let x?: to match only non-nil values and bind them, and case nil: to match nil explicitly.

3. Final Answer:

   Use 'case let x?' to bind only non-nil values, and 'case nil' for nil -> Option D

4. Quick Check:

   Optional binding uses 'case let x?' [OK]

Hint: Use 'case let x?' to match non-nil optionals [OK]

Common Mistakes:

• Matching nil after a catch-all case
• Using force unwrap (!) in case pattern
• Missing explicit nil case