Swift Enumerations

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  Keywords : Swift enum is a data type which is used to maintain set named values, Swift enumeration is a type to define a group of related values

Here we will learn enumerations in swift with examples and how to use swift enumerations to maintain group of related values, use enumeration with switch statements, swift enumerations with associated values, raw values and recursive enumerations in swift with examples.

Swift Enumerations

In swift enumeration is a data type which consists a set of related values and it allow us to use those defined values in our code in a type-safe manner.

 

The values whatever we defined in swift enumeration can be a string or a character or a value of integer or float. We can create different type of enumeration examples in swift like collection of colors, cards, animals and etc. 

 

The swift enumeration is powerful when we compare with other programming languages such as Objective-C and etc. because enumeration share their functionalities with structures and class. An enumeration in swift is a user defined so it contains methods, protocol and properties.

Swift Enumeration Syntax 

Generally in swift we use enum keyword to define a new enumeration followed by its name and the values in enumeration can be defined with case statement.

 

Following is the syntax of using enumeration in swift programming language.

 

enum enumname{

//Case A

//Case B

//Case C

---------

//Case N

}

If you observe above swift enumeration syntax we used enum keyword followed by its name and the values in enumeration defined using case statement.

 

Now we will see how to use enumerations in swift programming language with examples.

Swift Enumerations Example

Following is the example of defining and using enumerations in swift programming language.

 

enum Zoo {

case Tiger

case Lion

case Monkey

case Bear

case Elephant

}

var animal = Zoo.Tiger

if animal == .Tiger {

print("It’s a Tiger")

}

If you observe above enumeration example we defined enum “Zoo” with a set of related values using case keyword and we are accessing and comparing enumeration values based on our requirements.

 

If we are known about enumeration type then we can drop the type and use dot syntax to compare with enumeration values.

 

When we run above example in swift playground we will get result like as shown below

 

It's a Tiger

In swift we can define enumeration in another way like multiple case statements in a single line, separated by commas.

 

Following is the different approach of defining enumeration values.

 

enum Zoo {

case Tiger, Lion, Monkey, Bear, Elephant

}

var animal = Zoo.Tiger

if animal == .Tiger {

print("It’s a Tiger")

}

If you observe above example we defined enumeration values in a single line which separated by commas.

 

When we run above example in swift playground we will get result like as shown below

 

It's a Tiger

This is how we can define or declare enumeration in swift programming language based on our requirements.

Swift Enumeration with Switch Statement

Generally in swift enumeration we use case keyword to define enumeration values and swift allow us to declare individual values depend upon which pattern we will follow in our code. 

 

In swift we can use enumeration with Switch statement to match individual enumeration values.

 

Following is the example of using swift enumeration with Switch statement.

 

enum Zoo {

case Tiger

case Lion

case Monkey

case Bear

case Elephant

}

var animal = Zoo.Lion

switch animal {

case .Tiger:

print("It’s a Tiger")

case .Lion:

print("It’s a Lion")

case .Monkey:

print("It’s a Monkey")

case .Bear:

print("It’s a Bear")

case .Elephant:

print("It’s an Elephant")

}

If you observe above example we defined enumeration “Zoo” and checking variable with switch case statement to perform required statements based on variable value.

 

When we run above program in swift playground we will get result like as shown below.

 

It's a Lion

This is how we can use swift enumeration with switch case statements to perform required statements based on the defined conditions in swift programming language.

Swift Enumeration with Associated Values

In swift enumerations we can store associated values of any type along with the case values. The associated values will help us to store additional custom information along with the case values in swift enumerations.

 

In swift enumerations we can store any type of associated values but the value types can be different from each case of the enumeration based on our requirements.

 

For example if we want to store marks of students along with their names in Student enumeration then by using associated values we can store easily based on our requirements.

 

Now we will see how to use associated values with enumeration in swift programming language.

 

Following is the example of defining associated values for enumeration case statements in swift programming language.

 

enum Student {

case Name(String)

case Marks(Int,Int,Int)

}

var stname = Student.Name("Suresh Dasari")

var stmarks = Student.Marks(50, 70, 85)

//It Prints Name

switch stname {

case .Name (let studentName):

print("Student Name: \(studentName)")

case .Marks(let subject1, let subject2, let subject3):

print("Student Marks: \(subject1), \(subject2), \(subject3)")

default:

print("No Record Exists")

}

//It Print Marks

switch stmarks {

case .Name (let studentName):

print("Student Name: \(studentName)")

case .Marks(let subject1, let subject2, let subject3):

print("Student Marks: \(subject1), \(subject2), \(subject3)")

default:

print("No Record Exists")

}

If you observe above example we defined associated values of student along with case statements in swift programming language.

 

When we run above program in swift playground we will get result like as shown below 

 

Student Name: Suresh Dasari

Student Marks: 50, 70, 85

This is how we can use associated values with enumerations in swift programming language based on our requirements.

Swift Enumeration with Raw Values

As we discussed in swift enumerations associated values are used to store values of any type along with the case values. As an alternative to associated values, enumeration cases can come with prepopulated default values those are called a raw values.

 

In swift enumeration, raw values can be int, string, character, etc. and the raw value will be a same type for all the members in enumeration. The raw value for each member in enumeration must be unique.

 

Following is the example of assigning raw values to enumeration members in swift programming languages.

 

enum Zoo: Int {

case Tiger = 1

case Lion = 2

case Monkey = 3

case Bear = 4

case Elephant = 5

}

var lionVal = Zoo.Lion.rawValue

print(lionVal)

var  elephantVal = Zoo.Elephant.rawValue

print(elephantVal)

If you observe above example we defined enumeration “Zoo” with integer type and assigned default values of same type to each member in swift programming language.

 

When we run above program in swift playground we will get result like as shown below

 

2

5

If we didn’t assigned any raw values to enumeration case members explicitly, swift automatically will assign values for each member. Suppose if we defined enumeration with integer values, swift will assign raw values start from 0.

 

Following is the example enumeration with integer values without any defined raw values in swift programming language.

 

enum Zoo: Int {

case Tiger

case Lion

case Monkey

case Bear

case Elephant

}

var tigerVal = Zoo.Tiger.rawValue

print(tigerVal)

var  elephantVal = Zoo.Elephant.rawValue

print(elephantVal)

When we run above example in swift playground we will get result like as shown below.

 

0

4

Suppose if we defined enumeration with string values, swift will assign implicit value of each case is the raw value.

 

Following is the example enumeration with string values without any defined raw values in swift programming language.

 

enum Zoo: String {

case Tiger

case Lion

case Monkey

case Bear

case Elephant

}

var tigerVal = Zoo.Tiger.rawValue

print(tigerVal)

var  elephantVal = Zoo.Elephant.rawValue

print(elephantVal)

When we run above example in swift playground we will get result like as shown below.

 

Tiger

Elephant

This is how we can use raw values with enumeration members in swift programming language based on our requirements.

Swift Recursive Enumeration

In swift recursive enumeration is an enumeration that has another instance of the enumeration as the associated value for one or more of the enumeration cases

 

By using indirect keyword we can indicate that enumeration is a recursive and compiler will insert the necessary layer of indirection.

 

Following is the example of using recursive enumeration in swift programming language.

 

indirect enum ArithmeticExpression {

case num(Int)

case add(ArithmeticExpression, ArithmeticExpression)

}

func evaluate(_ expression: ArithmeticExpression) -> Int {

switch expression {

case .num(let value):

return value

case .add(let first, let last):

returnevaluate(first) + evaluate(last)

}

}

let a = ArithmeticExpression.num(34)

let b = ArithmeticExpression.num(234)

let addition = ArithmeticExpression.add(a, b)

print(evaluate(addition))

If you observe above example we defined recursive enumeration and performing addition operation in swift.

 

When we run above example in swift playground we will get result like as shown below.

 

286

This is how we can use recursive enumeration in swift programming language based on our requirements. 

 

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