Set creation and operations in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

How do you create an empty set of integers in Swift?

Use var numbers = Set<Int>() to create an empty set of integers.

beginner

What is the difference between a Set and an Array in Swift?

A Set stores unique values with no defined order, while an Array stores ordered values and can have duplicates.

beginner

How do you add an element to a Swift set?

Use the insert() method, for example: mySet.insert(5) adds the number 5 to the set.

intermediate

What does the union() operation do on two Swift sets?

It combines all unique elements from both sets into a new set, without duplicates.

intermediate

How can you find common elements between two sets in Swift?

Use the intersection() method to get a new set with elements found in both sets.

Which Swift code creates a set of strings?

A var fruits = ["apple", "banana"]

B var fruits = {"apple", "banana"}

C var fruits = ("apple", "banana")

D var fruits: Set<String> = ["apple", "banana"]

Option D correctly creates a Set of strings using Set<String> and array literal syntax.

What happens if you insert a duplicate element into a Swift set?

A The set ignores the duplicate and remains unchanged.

B The set converts to an array.

C The set throws a runtime error.

D The set adds the duplicate element again.

Sets only store unique elements, so inserting a duplicate does nothing.

Which method returns elements in one set but not in another?

A subtracting()

B intersection()

C union()

D insert()

subtracting() returns elements in the first set that are not in the second.

How do you check if a Swift set contains a specific element?

A set.has(element)

B set.includes(element)

C set.contains(element)

D set.find(element)

Use contains() to check if an element is in the set.

What is the result of setA.union(setB)?

A A set with elements only in setB

B A set with all unique elements from setA and setB

C A set with elements only in setA

D A set with elements common to setA and setB

union() combines all unique elements from both sets.

Explain how to create a set in Swift and add elements to it.

Think about starting empty and then putting things inside.

Describe the difference between union, intersection, and subtracting operations on sets.

Imagine mixing, matching, and removing items from two baskets.