Swift variable name with ` (backtick)

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I was browsing Alamofire sources and found variable which name is backtick escaped in this source file

open static let `default`: SessionManager = {
    let configuration = URLSessionConfiguration.default
    configuration.httpAdditionalHeaders = SessionManager.defaultHTTPHeaders

    return SessionManager(configuration: configuration)
}()

However in places where variable is used there are no backticks. What's the purpose of backticks?


According to the Swift documentation :

To use a reserved word as an identifier, put a backtick before and after it. For example, class is not a valid identifier, but `class` is valid. The backticks are not considered part of the identifier; `x` and x have the same meaning.

In your example, default is a swift reserved keyword, that's why backticks are needed.

Backticks in `Swift`, Have a nicer codebase by using backticks in Swift. to self and keep it's name (​or change the name and use strongSelf variable name): There's deparse () which is also used by print.default (): > deparse (quote (`5`), width.cutoff = 500L, backtick = TRUE) "`5`" > deparse (quote (`a`), width.cutoff = 500L, backtick = TRUE) "a" > deparse (quote (`repeat`), width.cutoff = 500L, backtick = TRUE) "`repeat`"


Example addendum to the accepted answer, regarding using reserved word identifiers, after they have been correctly declared using backticks.

The backticks are not considered part of the identifier; `x` and x have the same meaning.

Meaning we needn't worry about using the backticks after identifier declaration (however we may):

enum Foo {
    case `var`
    case `let`
    case `class`
    case `try`
}

/* "The backticks are not considered part of the identifier; 
    `x` and x have the same meaning"                          */
let foo = Foo.var
let bar = [Foo.let, .`class`, .try]
print(bar) // [Foo.let, Foo.class, Foo.try]

Swift: Backticks should not be used around symbol names, Therefore this rule ignores backticks around parameter names. var protectionSpace: NSURLProtectionSpace = NSURLProtectionSpace( host: host, port: port, `  To use a reserved word as an identifier, put a backtick before and after it. For example, class is not a valid identifier, but `class` is valid. The backticks are not considered part of the identifier; `x` and x have the same meaning. In your example, default is a swift reserved keyword, that's why backticks are needed.


Simply put, by using backticks you are allowed to use reserved words for variable names etc.

var var = "This will generate an error" 

var `var` = "This will not!"

Lexical Structure, Keywords other than inout , var , and let can be used as parameter names in a function declaration or function call without being escaped with backticks. When a  A variable without the dollar sign $ only provides the name of the variable. You can also create a variable that takes its value from an existing variable or number of variables. The following command defines a new variable called drink_of_the_Year, and assigns it the combined values of the my_boost and this_year variables:


Beginning Swift: Master the fundamentals of programming in Swift 4, When you assign the value of a variable or constant as you create it, the Swift may be used as variable names if enclosed in backticks (for example, `Int`:Int  Template literals are enclosed by the backtick (` `) (grave accent) character instead of double or single quotes. Template literals can contain placeholders. These are indicated by the dollar sign and curly braces ($ {expression}). The expressions in the placeholders and the text between the backticks (` `) get passed to a function.


How to use Swift reserved keywords as constants or variables, Since Swift has this feature to infer the variable or constant a variable 'var' with the same name as the reserved Swift keyword. Another common mistake would be using the reserved keywords without any backticks at all  Since, print("I love Swift.") function adds a line break, the statement print("I also love Taylor Swift") outputs in a new line. Example 4: Printing multiple items using single print function You can also print multiple items in a single print statement and add separator between those items as:


How to name constant and variable with reserved keywords in Swift , in Swift. If you want to name the variables and constants with keywords we can do that by surrounding the names with the backticks(). You use variables and constants in Swift to store information. It’s that simple! Variables are the “things” in your code, like numbers, text, buttons and images. Every bit of information your app uses, is stored in a variable or a constant. Knowing how variables work is the first step of learning iOS development. In this article you’ll