Swift – Keywords

Every programming language has some set of reserved words that are used for some internal process or represent some predefined actions such words are known as keywords or reserve words. You are not allowed to use these reserved words as a variable name, constant name, or any other identifier. But if you want to want to use keywords as identifiers then you have to use the backtick (`) before and after the specified keyword. For example, a struct is a keyword it is not an identifier but `struct` is a valid identifier. backtick does not work with identifiers like `a` and a both are the same. In Swift, keywords are categorized in four categories according to their usage:

• Keyword in declaration
• Keyword in statement
• Keywords in expression and type
• Keywords in the specific context
• keywords that begin with the number sign
• Keyword used in the patterns(_)

Keywords used in the declaration

Following are the keywords used in the declaration:

associatedtype	class	deinit	enum	extension	fileprivate	func	import
init	inout	internal	let	open	operator	private	precedencegroup
protocol	public	rethrows	static	struct	subscript	typealias	var

Example:

Swift

// Swift program to illustrate Keywords used in the declaration
import Swift

// Creating structure
// Using struct keyword
struct geeksforgeeks{

    // Creating variable
    // using var keyword
    var employeeName = "Mohit"
    var employeeID = 1234
}

// Creating the instance of geeksforgeeks structure
var myinstance = geeksforgeeks()

// Accessing the properties of geeksforgeeks structure
print("Employee Name:", myinstance.employeeName)
print("Employee ID:", myinstance.employeeID)

Output:

Employee Name: Mohit
Employee ID: 1234

Keywords used in statements

Following are the keywords used in the statement:

break	case	catch	continue	default	defer
do	else	fallthrough	for	guard	if
in	repeat	return	throw	switch	where	while

Example:

Swift

// Swift program to illustrate Keywords used in statements
import Swift

// Finding the age group
let EmpAge = 70

// Using if keyword for the condition
if (EmpAge >= 60)
{

    // Print statement
    print("Senior Citizen")
}

// Using else keyword for the condition
else if (EmpAge >= 40)
{

    // Print statement
    print("Middle age")
}

else
{

    // Print statement
    print("Young")
}

Output:

Senior Citizen

Keywords used in expression and type

Following are the keywords used in the expression and type:

Any	as	catch	false	is
nil	rethrows	self	Self	super
throw	throws	true	try

Example:

Swift

// Swift program to illustrate Keywords used in expression and type
import Swift

// Creating  a class
class GeeksforGeeks
{

    // Class method
    func EmployeName()
    {
        print("Hello! My name is Govind")

    }
}

// Creating another class
// It is the child class of GeeksforGeeks
class Gemployee : GeeksforGeeks
{

    // Overriding method
    override func EmployeName()
    {

        // Here we are accessing the parent class method
        // Using super keyword
        super.EmployeName()
        print("I m working in the HR department")
    }
}

// Creating the object of the child class
let obj = Gemployee()

// Accessing the method of child class
obj.EmployeName()

Output:

Hello! My name is Govind
I m working in the HR department

Keywords used in the specific context

In Swift language, some keywords are used in a specific context, and outside the context of the grammar, they are allowed to use as identifiers. Following are the keywords used in the specific context:

associativity	convenience	didSet	dynamic	final	get	indirect	infix	lazy
left	mutating	none	nonmutating	optional	override	postfix	precedence	prefix
Protocol	required	right	set	some	Type	unowned	weak	willSet

Example:

Swift

// Swift program to illustrate Keywords used in the specific context
import Swift

// Creating a structure
struct GeeksforGeeks
{

    // Creating variables
    var myval: String

    // Creating a function that will mutate
    // Using mutate keyword
    mutating func myfunction() {
        self.myval = "Mohit"
    }
}

// Creating variable of GeeksforGeeks structure
var obj = GeeksforGeeks(myval: "Rohan")

// Calling the function
obj.myfunction()
print(obj.myval)

Output:

Mohit

Keywords that begin with the number sign

Following are the keywords that begin with the number sign(#):

#available	#colorLiteral	#column	#dsohandle	#elseif	#else	#endif
#error	#fileID	#fileLiteral	#filePath	#file	#function	#if
#imageLiteral	#keyPath	#line	#selector	#sourceLocation	#warning

Example:

Swift

// Swift program to illustrate Keywords that begin with the number sign
import Swift

// Creating a function
func GeeksforGeeks()
{
    // Here we use #function keyword to
    // display the name of the function
    print("I am the \(#function)")
}

// Calling the function
GeeksforGeeks()

Output:

I am the GeeksforGeeks()

Keyword used in the patterns(_)

In Swift, underscore(_) keyword is used in patterns. Suppose you want to print a pattern 14 times then you can use this keyword.

Example:

Swift

// Swift program to illustrate keyword used in the patterns(_)
import Swift

// Printing GeeksforGeeks 14 time
// Using _keyword
for _ in 1...10 {
    print("GeeksforGeeks")
}

Output:

GeeksforGeeks
GeeksforGeeks
GeeksforGeeks
GeeksforGeeks
GeeksforGeeks
GeeksforGeeks
GeeksforGeeks
GeeksforGeeks
GeeksforGeeks
GeeksforGeeks