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
Explore
Swift Introduction
Swift Data Types
Swift Control Flow
Swift Functions
Swift Collections
Swift OOPs
Swift Additional Topics