Character and String types in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Swift code?

Consider the following Swift code snippet. What will it print?

Swift

let greeting: String = "Hello, 👋"
print(greeting.count)

A 7

B 8

C 9

D 6

💡 Hint

Remember that some emoji count as a single character in Swift strings.

The string "Hello, 👋" contains 7 visible characters plus the emoji 👋 which counts as one character, making the total count 8.

❓ Predict Output

intermediate

What is the output of this Swift code using Character type?

What will this Swift code print?

Swift

let letter: Character = "A"
print(letter.isLetter)

A nil

B false

C Compilation error

D true

💡 Hint

Check if the Character type has a property to check if it is a letter.

The Character type in Swift has the property isLetter which returns true if the character is a letter.

❓ Predict Output

advanced

What is the output of this Swift code with Unicode scalars?

What will this Swift code print?

Swift

let heart = "\u{2764}\u{FE0F}"
print(heart.count)

A 1

B 2

C 3

D 0

💡 Hint

Unicode scalars can combine to form a single character.

The two Unicode scalars combine to form a single emoji character, so the count is 1.

❓ Predict Output

advanced

What is the output of this Swift code using string interpolation with characters?

What will this Swift code print?

Swift

let char1: Character = "S"
let char2: Character = "w"
let char3: Character = "i"
let char4: Character = "f"
let char5: Character = "t"
let word = "\(char1)\(char2)\(char3)\(char4)\(char5)"
print(word)

A S w i f t

B [S, w, i, f, t]

C Swift

D Compilation error

💡 Hint

String interpolation joins characters into a string without spaces.

String interpolation concatenates the characters into the string "Swift" without spaces.

🧠 Conceptual

expert

How many characters are in this Swift string?

Consider the Swift string let s = "e\u{301}". How many characters does s.count return?

A 1

B 2

C 0

D Compilation error

💡 Hint

Unicode combining marks combine with base characters to form one character.

The string contains the letter 'e' plus a combining acute accent. Swift counts this as one character.

Practice

1. Which Swift type is used to store a single letter or symbol?

easy

A. Bool

B. String

C. Character

D. Int

Solution

1. Step 1: Understand the types

   Character stores exactly one letter or symbol, while String stores many characters.

2. Step 2: Match the description

   Since the question asks for a single letter or symbol, Character is the correct type.

3. Final Answer:

   Character -> Option C

4. Quick Check:

   Single letter = Character [OK]

Hint: Single letter? Use Character type [OK]

Common Mistakes:

• Confusing Character with String
• Choosing Int or Bool which are not text types

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

easy

A. var name: String = "John"

B. var name = 'John'

C. var name = John

D. var name: Character = "John"

Solution

1. Step 1: Check syntax for String declaration

   In Swift, String literals must be in double quotes, and type can be declared explicitly.

2. Step 2: Analyze options

   var name: String = "John" uses var with type String and double quotes correctly. var name = 'John' uses single quotes which is invalid. var name = John misses quotes. var name: Character = "John" uses Character type but assigns multiple characters.

3. Final Answer:

   var name: String = "John" -> Option A

4. Quick Check:

   String uses double quotes and correct type [OK]

Hint: Use double quotes for String, single char needs Character [OK]

Common Mistakes:

• Using single quotes for String
• Assigning multiple characters to Character
• Missing quotes around text

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

let letter: Character = "A"
let word: String = "Apple"
print(letter)
print(word)

medium

A. Error: Cannot print Character

B. Apple\nA

C. letter\nword

D. A\nApple

Solution

1. Step 1: Understand variable types and values

   letter is a Character with value "A"; word is a String with value "Apple".

2. Step 2: Analyze print statements

   print(letter) outputs "A" and print(word) outputs "Apple" on separate lines.

3. Final Answer:

   A\nApple -> Option D

4. Quick Check:

   Print Character then String = A\nApple [OK]

Hint: Print shows Character or String as text directly [OK]

Common Mistakes:

• Confusing order of print statements
• Thinking Character cannot be printed
• Expecting variable names printed

4. Identify the error in this Swift code:

let symbol: Character = "AB"

medium

A. Missing semicolon at end

B. Character cannot hold more than one character

C. String type should be used instead of Character

D. Quotes should be single quotes

Solution

1. Step 1: Check Character assignment rules

   Character type can only hold exactly one character or symbol.

2. Step 2: Analyze the code

   "AB" has two characters, so assigning it to Character causes an error.

3. Final Answer:

   Character cannot hold more than one character -> Option B

4. Quick Check:

   Character = single char only [OK]

Hint: Character holds one char; multiple chars need String [OK]

Common Mistakes:

• Using multiple characters for Character type
• Thinking semicolon is required
• Using single quotes for strings

5. You want to create a Swift function that counts how many vowels are in a given String. Which approach correctly uses Character and String types?

hard

A. Iterate over the String's characters and check if each Character is a vowel

B. Convert the String to Int and count vowels

C. Use Character type to store the whole String and count vowels

D. Use Bool type to store vowels and count them

Solution

1. Step 1: Understand the problem

   We need to check each letter in a String to see if it is a vowel.

2. Step 2: Choose correct types and method

   Iterating over a String gives Characters one by one, which can be checked against vowels.

3. Step 3: Analyze options

   Iterate over the String's characters and check if each Character is a vowel correctly describes iterating over Characters in a String. Options A, B, and D misuse types or concepts.

4. Final Answer:

   Iterate over the String's characters and check if each Character is a vowel -> Option A

5. Quick Check:

   Check each Character in String for vowels [OK]

Hint: Loop over String characters to check each letter [OK]

Common Mistakes:

• Trying to convert String to Int for counting
• Using Character to hold whole String
• Using Bool incorrectly to count vowels