What is Swift - Interactive Quiz & Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print a greeting in Swift.

Swift

print([1])

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

AHello Swift

BHello, Swift!

C'Hello, Swift!'

D"Hello, Swift!"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the double quotes around the string.

Using single quotes instead of double quotes.

In Swift, strings must be enclosed in double quotes when printed.

2fill in blank

medium

Complete the code to declare a variable named greeting with the value "Hello".

Swift

var greeting = [1]

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

A"Hello"

B'Hello'

CHello

Dgreeting

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning the string without quotes.

Using single quotes instead of double quotes.

In Swift, string values must be enclosed in double quotes when assigned to variables.

3fill in blank

hard

Fix the error in the code to correctly declare a constant named pi with value 3.14.

Swift

let pi = [1]

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

A3,14

B"3.14"

C3.14

Dpi

Attempts:

3 left

💡 Hint

Common Mistakes

Using a comma instead of a dot for decimals.

Putting the number inside quotes making it a string.

Numbers in Swift use a dot for decimals, not a comma.

4fill in blank

hard

Fill both blanks to create a function named greet that prints a message.

Swift

func [1]() {
    print([2])
}

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

Agreet

B"Welcome to Swift!"

Cgreeting

DWelcome

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name instead of a string in print.

Missing parentheses after the function name.

The function name is greet and it prints the string "Welcome to Swift!".

5fill in blank

hard

Fill all three blanks to create a dictionary with keys and values.

Swift

let [1] = [[2]: [3]]

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

Aperson

B"name"

C"Alice"

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around string keys or values.

Using a variable name instead of a string for the key.

This creates a dictionary named person with key "name" and value "Alice".

Practice

1. What is Swift primarily used for?

easy

A. Designing graphics

B. Building websites

C. Creating apps for Apple devices

D. Managing databases

Solution

1. Step 1: Understand Swift's main purpose

   Swift is designed mainly for developing software on Apple platforms like iPhone and Mac.

2. Step 2: Compare options with Swift's use

   Only Creating apps for Apple devices matches this use; others relate to different fields.

3. Final Answer:

   Creating apps for Apple devices -> Option C

4. Quick Check:

   Swift = Apple app development [OK]

Hint: Swift is Apple's language for apps [OK]

Common Mistakes:

• Thinking Swift is for websites
• Confusing Swift with database tools
• Assuming Swift is for graphic design

2. Which of the following is the correct way to declare a variable in Swift?

easy

A. var name = "John"

B. variable name = "John"

C. let name := "John"

D. dim name = "John"

Solution

1. Step 1: Recall Swift variable declaration syntax

   Swift uses 'var' to declare variables and '=' to assign values.

2. Step 2: Check each option

   var name = "John" matches Swift syntax; others use incorrect keywords or symbols.

3. Final Answer:

   var name = "John" -> Option A

4. Quick Check:

   Variable declaration = var name = value [OK]

Hint: Use 'var' to declare variables in Swift [OK]

Common Mistakes:

• Using 'variable' instead of 'var'
• Using ':=' instead of '='
• Using 'dim' from other languages

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

let speed = 60
let time = 2
let distance = speed * time
print(distance)

medium

A. 120

B. 62

C. Error

D. 60

Solution

1. Step 1: Calculate the multiplication

   speed (60) multiplied by time (2) equals 120.

2. Step 2: Understand print output

   The print statement outputs the value of distance, which is 120.

3. Final Answer:

   120 -> Option A

4. Quick Check:

   60 * 2 = 120 [OK]

Hint: Multiply variables and print result [OK]

Common Mistakes:

• Adding instead of multiplying
• Confusing variable names
• Expecting syntax error

4. Identify the error in this Swift code:

let age = 25
age = 30
print(age)

medium

A. Missing semicolon after print statement

B. Cannot assign a new value to a constant

C. Variable 'age' is not declared

D. Print statement syntax is incorrect

Solution

1. Step 1: Check variable declaration

   'age' is declared with 'let', making it a constant that cannot change.

2. Step 2: Identify assignment error

   Trying to assign 30 to 'age' causes an error because constants cannot be reassigned.

3. Final Answer:

   Cannot assign a new value to a constant -> Option B

4. Quick Check:

   let means constant, no reassignment [OK]

Hint: 'let' means constant, no change allowed [OK]

Common Mistakes:

• Thinking 'let' allows reassignment
• Expecting semicolons in Swift
• Misreading print syntax

5. You want to write a Swift program that safely calculates the average of an array of numbers, but the array might be empty. Which approach best uses Swift's safety features?

hard

A. Force unwrap the array count and sum

B. Divide the sum by the array count without checks

C. Ignore empty arrays and return zero always

D. Use optional binding to check if the array is empty before dividing

Solution

1. Step 1: Understand the problem with empty arrays

   Dividing by zero (array count 0) causes a runtime error.

2. Step 2: Use optional binding for safety

   Optional binding lets you check if the array has elements before dividing, avoiding errors.

3. Step 3: Evaluate options

   Use optional binding to check if the array is empty before dividing uses Swift's safety features correctly; others risk errors or ignore safety.

4. Final Answer:

   Use optional binding to check if the array is empty before dividing -> Option D

5. Quick Check:

   Optional binding = safe checks [OK]

Hint: Check array emptiness with optional binding before dividing [OK]

Common Mistakes:

• Dividing without checking for zero count
• Force unwrapping optionals causing crashes
• Ignoring empty arrays without handling