guard let Unwrapping क्या है

guard let जांचता है कि एक value मौजूद है, और अगर नहीं है, function बिना इसके continue करने की कोशिश करने के बजाय तुरंत निकल जाता है।

In this page:

Basic guard let
Chaining Multiple guard let Unwraps

Syntax

swift

func name(param: Type?) {
    guard let unwrapped = param else {
        return
    }
    // use unwrapped
}

Basic guard let

guard let एक optional unwrap करता है और, अगर यह fail हो, else block execute करता है जिसे current scope छोड़ना चाहिए, आमतौर पर return के ज़रिए।

उदाहरण: Basic guard let

markup

// Define the function `printUppercased` taking `text`
func printUppercased(_ text: String?) {
    // Unwrap `text` into `text`, or bail out via the else branch
    guard let text = text else {
        // Print "No text provided" to the console
        print("No text provided")
        return
    }
    // Print `text.uppercased()` to the console
    print(text.uppercased())
}
printUppercased("hello")
printUppercased(nil)

Chaining Multiple guard let Unwraps

कई optionals एक single guard let में unwrap किए जा सकते हैं, सभी commas से अलग, किसी function के top पर validation logic compact रखते हुए।

उदाहरण: Chaining Multiple guard let Unwraps

markup

// Define the function `describe` taking `name`, `age`
func describe(name: String?, age: Int?) {
    // Unwrap `name, let age = age` into `name`, or bail out via the else branch
    guard let name = name, let age = age else {
        // Print "Missing information" to the console
        print("Missing information")
        return
    }
    // Print "\(name) is \(age) years old" to the console
    print("\(name) is \(age) years old")
}
describe(name: "Kim", age: 28)
describe(name: nil, age: 28)

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guard let Unwrapping क्या है

Basic guard let

Chaining Multiple guard let Unwraps

Chapter Quiz — Complete all 8 topics to unlock

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