If case let

This concise syntax provides a convenient shortcut when you want to match a single case without writing a full-blown switch statement. Although it might seem a bit backward at first, once you grasp its power, you'll find it quite handy.

The Scenario

Imagine you're working with the Swift Result type, capturing the results of a throwing expression (such as loading data from a file). Here's how you'd typically handle it:

import Foundation

let result = Result {
    try Data(
        contentsOf: URL(
            string: "https://wesleydegroot.nl"
        )!
    )
}

switch result {
case .success(let data):
    // Do something with the data
    print(data)
case .failure(let error):
    // Handle the error
    print(error)
}

The Syntax

Now, let's introduce the if case let syntax. It allows you to directly match a specific case without the need for a full switch statement:

if case let .failure(error) = result {
    // Handle the error
    print(error)
}

Alternatively, you can use the slightly more concise form:

if case .failure(let error) = result {
    // Handle the error
    print(error)
}

Adding Conditions

You can further filter the matching cases by adding a where clause. For example:

if case let .success(data) = result, data.count > 100 {
    // Process the data (only if its count exceeds 100)
}

Beyond Switch Statements

The case let syntax isn't restricted to switch statements. You can also use it in if statements or even guard statements:

// Using an if statement
if case let .success(data) = result {
    // Handle the success case
}

// Using an alternate form
if case .success(let data) = result {
    // Handle the success case
}

// Using a guard statement
guard case let .success(data) = result, data.count > 100 else {
    return
}

// Continue with further processing

Download Swift Playground

Wrap up

In this post, you learned about the if case let syntax in Swift, which provides a concise way to match a specific case without the need for a full switch statement. This syntax is particularly useful when you're working with types like Result and want to handle the success or failure cases separately. By using if case let, you can streamline your code and make it more readable.

Conclusion

The if case let syntax in Swift is a powerful feature that allows you to match specific cases without the need for a full switch statement. This concise syntax is particularly useful when you're working with types like Result and want to handle the success or failure cases separately. By using if case let, you can streamline your code and make it more readable. Give it a try in your next project and see how it can help you write cleaner, more maintainable code.

Read more

• How to monitor network in SwiftUI • 3 minutes reading time.
• What is @frozen • 5 minutes reading time.
• Snippet: @EnvironmentVariable • 1 minutes reading time.

Share