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 w3wiki{ // Creating variable // using var keyword var employeeName = "Mohit" var employeeID = 1234 } // Creating the instance of w3wiki structure var myinstance = w3wiki() // Accessing the properties of w3wiki 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 w3wiki { // Class method func EmployeName() { print ( "Hello! My name is Govind" ) } } // Creating another class // It is the child class of w3wiki class Gemployee : w3wiki { // 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 w3wiki { // Creating variables var myval: String // Creating a function that will mutate // Using mutate keyword mutating func myfunction() { self .myval = "Mohit" } } // Creating variable of w3wiki structure var obj = w3wiki(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 w3wiki() { // Here we use #function keyword to // display the name of the function print ( "I am the \(#function)" ) } // Calling the function w3wiki() |
Output:
I am the w3wiki()
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 w3wiki 14 time // Using _keyword for _ in 1...10 { print ( "w3wiki" ) } |
Output:
w3wiki w3wiki w3wiki w3wiki w3wiki w3wiki w3wiki w3wiki w3wiki w3wiki
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