Tuples for grouped values in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this tuple unpacking?

Consider the following Swift code that uses a tuple to group values and then unpacks them. What will be printed?

Swift

let person = (name: "Alice", age: 30, city: "Paris")
let (name, age, city) = person
print("\(name) is \(age) years old and lives in \(city).")

A name is 30 years old and lives in city.

B Alice is 30 years old and lives in Paris.

C (name, age, city)

D 30 is Alice years old and lives in Paris.

💡 Hint

Look at how the tuple is unpacked into variables and used in the print statement.

The tuple 'person' has named elements. Unpacking assigns each element to variables 'name', 'age', and 'city'. The print statement uses these variables to form the output string.

🧠 Conceptual

intermediate

Which tuple declaration is correct in Swift?

You want to create a tuple that groups a person's name as a String and age as an Int. Which of the following declarations is correct?

A let person = (name: "Bob", age: "25")

B let person = ("Bob", "25")

C let person: (String, Int) = ("Bob", 25)

D let person: (name: String, age: Int) = ("Bob", "25")

💡 Hint

Check the types of each element in the tuple and their matching values.

Option C correctly declares a tuple with types (String, Int) and assigns matching values. Option C has age as a String instead of Int. Option C uses Strings for both elements without type annotation. Option C mismatches types by assigning a String to age which expects Int.

🔧 Debug

advanced

Why does this tuple code cause a compile error?

Examine the Swift code below. Why does it cause a compile-time error?

Swift

let coordinates = (x: 10, y: 20)
let (a, b, c) = coordinates
print(a, b, c)

A The tuple elements must be accessed only by name, not by unpacking.

B The tuple elements are named, so you cannot unpack them into variables.

C You cannot print multiple variables separated by commas in Swift.

D The tuple 'coordinates' has only two elements, but three variables are used to unpack it.

💡 Hint

Count the number of elements in the tuple and the number of variables used to unpack.

The tuple 'coordinates' has two elements (x and y). Trying to unpack into three variables (a, b, c) causes a compile error because the counts do not match.

📝 Syntax

advanced

Which option correctly creates a tuple with mixed types?

You want to create a tuple with a String, an Int, and a Bool in Swift. Which of the following is syntactically correct?

A let info = ("John", 42, true)

B let info = ("John"; 42; true)

C let info = ["John", 42, true]

D let info = {"John", 42, true}

💡 Hint

Remember the syntax for tuples uses parentheses and commas.

Option A uses parentheses and commas, which is the correct syntax for tuples. Option A uses semicolons which is invalid. Option A uses square brackets which create arrays, not tuples. Option A uses curly braces which is invalid syntax here.

🚀 Application

expert

What is the value of 'result' after this tuple swap?

Given the following Swift code that swaps two values using tuples, what is the value of 'result' after execution?

Swift

var a = 5
var b = 10
(a, b) = (b, a)
let result = (a, b)

A (10, 5)

B (5, 10)

C (0, 0)

D (a, b)

💡 Hint

Look at how the tuple assignment swaps the values of 'a' and 'b'.

The tuple assignment swaps the values of 'a' and 'b'. Initially a=5 and b=10, after swap a=10 and b=5. So 'result' is (10, 5).

Practice

1. What is a tuple in Swift used for?

easy

A. Defining a function

B. Creating a new class type

C. Grouping multiple values into a single compound value

D. Declaring a constant

Solution

1. Step 1: Understand tuple purpose

   Tuples combine multiple values into one grouped value without creating a new type.

2. Step 2: Compare with other options

   Classes, functions, and constants serve different purposes unrelated to grouping multiple values simply.

3. Final Answer:

   Grouping multiple values into a single compound value -> Option C

4. Quick Check:

   Tuple = grouped values [OK]

Hint: Tuples bundle values together simply [OK]

Common Mistakes:

• Confusing tuples with classes or structs
• Thinking tuples define functions
• Assuming tuples declare constants only

2. Which of the following is the correct syntax to declare a tuple with an Int and a String in Swift?

easy

A. let person: (Int, String) = (25, "Alice")

B. let person = Int, String = (25, "Alice")

C. let person = Int: 25, String: "Alice"

D. let person: Int, String = (25, "Alice")

Solution

1. Step 1: Check tuple declaration syntax

   Correct tuple syntax uses parentheses with types inside, then assigns values in parentheses.

2. Step 2: Validate each option

   let person: (Int, String) = (25, "Alice") correctly declares a tuple type and assigns matching values. Others have syntax errors or wrong format.

3. Final Answer:

   let person: (Int, String) = (25, "Alice") -> Option A

4. Quick Check:

   Tuple syntax = (Type1, Type2) = (value1, value2) [OK]

Hint: Use parentheses for tuple types and values [OK]

Common Mistakes:

• Omitting parentheses around types
• Trying to declare types outside tuple parentheses
• Using incorrect colon placement

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

let coordinates = (x: 10, y: 20)
print(coordinates.x + coordinates.y)

medium

A. Error: Cannot access tuple elements by label

B. 10 20

C. coordinates.xcoordinates.y

D. 30

Solution

1. Step 1: Understand tuple with labels

   The tuple has labels x and y with values 10 and 20 respectively.

2. Step 2: Calculate the sum

   Adding coordinates.x (10) and coordinates.y (20) results in 30.

3. Final Answer:

   30 -> Option D

4. Quick Check:

   10 + 20 = 30 [OK]

Hint: Access tuple values by labels with dot notation [OK]

Common Mistakes:

• Trying to print tuple without accessing elements
• Confusing tuple labels with dictionary keys
• Assuming tuple elements can't be accessed by label

4. Identify the error in this Swift code snippet:

let person = (name: "Bob", age: 30)
print(person[0])

medium

A. Tuples cannot be accessed by index using square brackets

B. Tuple labels must be strings, not integers

C. Tuple elements must be accessed with parentheses, not brackets

D. The tuple declaration is missing type annotations

Solution

1. Step 1: Check tuple access method

   Tuples in Swift are accessed by position using dot and index (e.g., .0), not square brackets.

2. Step 2: Analyze the code error

   Using person[0] causes an error because square brackets are not valid for tuple indexing.

3. Final Answer:

   Tuples cannot be accessed by index using square brackets -> Option A

4. Quick Check:

   Use dot and number for tuple index, not brackets [OK]

Hint: Use dot and number for tuple index, not brackets [OK]

Common Mistakes:

• Using square brackets to access tuple elements
• Confusing tuples with arrays or dictionaries
• Assuming type annotations are mandatory for tuples

5. Given a function that returns a tuple with a person's name and age, how can you extract these values into separate variables?

func getPerson() -> (String, Int) {
    return ("Emma", 28)
}
// Extract values here

hard

A. let person = getPerson()
let personName = person[0]
let personAge = person[1]

B. let (personName, personAge) = getPerson()

C. let personName = getPerson().name
let personAge = getPerson().age

D. let personName, personAge = getPerson()

Solution

1. Step 1: Understand tuple unpacking

   Swift allows unpacking tuple return values directly into variables using parentheses.

2. Step 2: Evaluate options

   let (personName, personAge) = getPerson() correctly unpacks both values at once. let person = getPerson() let personName = person[0] let personAge = person[1] uses invalid indexing. let personName = getPerson().name let personAge = getPerson().age attempts to access nonexistent labels. let personName, personAge = getPerson() has invalid syntax.

3. Final Answer:

   let (personName, personAge) = getPerson() -> Option B

4. Quick Check:

   Tuple unpacking uses let (a, b) = tuple [OK]

Hint: Unpack tuples with let (a, b) = function() [OK]

Common Mistakes:

• Using square brackets to access tuple elements
• Attempting to access tuple elements by nonexistent labels
• Incorrect syntax for unpacking tuples