Swift Sets

Question 1

What does an “array” do?

Answer 1

Stores values of the same type in an ordered list.

Question 2

What does a “set” do?

Answer 2

It stores distinct values of the same type in a collection with no defined ordering.

Question 3

When is a good time to use a “set” instead of an array? (List two examples)

Answer 3

1. When the order of items is not important

2. When you need to ensure that an item appears only once.

Question 4

1. What is a hash value?

2. Provide an example

Answer 4

1. An Int value that is the same for all objects that compare equally.
2. (EX.) - if a == b, the hash value of a is equal to the hash value of b

Question 5

A type must be _____ in order to be stored in a set.

Answer 5

hashable (The type must provide a way to compute a “hash value” for itself)

Question 6

What Swift types are hashable by default? (List 2)

Answer 6

1. All of Swift’s basic types such as String, Int, Double, and Bool.
2. Enumeration case values without associated values.

Question 7

Data types that are hashable can be used as 1. ____ or 2. ______.

Answer 7

1. Set value types

2. Dictionary key types.

Question 8

Create an empty set of a certain type using the initializer syntax

Answer 8

var setName = Set( )

Question 9

Initialize a set with an array literal

Answer 9

var arrayLiteralSet: Set = [“ItemOne”, “ItemTwo”, “ItemThree”]

Question 10

Initialize a set with an array literal using Swift’s type inference to assume the type

Answer 10

var arrayLiteralSet: Set = ["ItemOne", "ItemTwo", "ItemThree"]
//Because all values are same type swift can infer that Set is correct.

Question 11

You access and modify a set through it’s 1)_____ and 2)_____.

Answer 11

1. Methods

2. Properties

Question 12

You can add a new item into a set by calling the set’s ______ method.

Answer 12

insert(_: )

Question 13

You can check whether a sets count property is equal to 0 by using the ___ property.

Answer 13

isEmpty

Question 14

Use isEmpty in an if statement

Answer 14

if setName.isEmpty {
instructions if true
} else {
instructions if false
}

Question 15

You can remove an item from a set by calling the set’s _____ method

Answer 15

remove(_: )

Question 16

All items in a set can be removed with its _____ method.

Answer 16

removeAll( )

Question 17

To check whether a set contains a particular item, use the _____ method.

Answer 17

contains(_: )

Question 18

You can iterate over the values in a set with a _____ loop

Answer 18

for-in

Question 19

Swift’s set type does not have ____ _____.

Answer 19

Defined ordering

Question 20

To iterate over the values of a set in a specific order, use the _____ method.

Answer 20

sorted( )

Question 21

What will happen if you use a sets sorted( ) method on it?

Answer 21

It will return the set’s elements as an array sorted using the < operator.

Question 22

Use the 1. _____ method to create a new set with only the values common to both sets.

Answer 22

1. intersection(_: )

Question 23

Use the 1. ______ method to create a new set with values in either set, but not both.

Answer 23

1. symmetricDifference(_: )

Question 24

Use the 1. ______ method to create a new set with all the values in both sets

Answer 24

1. union(_: )

Question 25

Use the 1. _______ method to create a new set with values not in the specified set.

Answer 25

1. subtracting(_: )

Question 26

Use the _____ operator to determine whether two sets contain all of the same values

Answer 26

"is equal" (==)

Question 27

Use the ______ method to determine whether all of the values of a set are contained in a specific set.

Answer 27

isSubset(of: )

Question 28

Use the _______ method to determine whether a set contains all of the values in a specified set.

Answer 28

isSuperset(of: )

Question 29

Use the 1. ______ or 2. ______ methods to determine whether a set is a subset or superset, but not equal to, a specified set.

Answer 29

1. isStrictSubset(of: ) | 2. isStrictSuperset(of: )

Question 30

Use the ______ method to determine whether two sets have no values in common.

Answer 30

isDisjoint(with: )

Question 31

Why would set "a" be a "superset" of set "b"?

Answer 31

Because set "a" contains all elements in set "b"

Question 32

Why would set "b" be a "subset" of set "a"?

Answer 32

Because all elements in set "b" are also contained in set "a"

Question 33

Why would set "b" and set "c" be "disjoint" with one another?

Answer 33

Because they share no elements in common.