Leveraging if/else Statements as Expressions in Swift 5.9

Swift 5.9, introduced with Xcode 15, brings a powerful feature that allows developers to use if/else statements as expressions. This enhancement enables you to return values from functions, assign values to variables, and declare variables using if/else constructs, simplifying your code and making it more expressive. In this guide, we’ll explore how to use if/else statements as expressions in Swift 5.9 and see some practical examples.

Using if/else Statements as Expressions:

The ability to use if/else statements as expressions means that the value of the chosen branch becomes the value of the overall expression. Here’s a simple example of how you can use this feature:

// Function to determine a discount percentage based on the customer's loyalty level
func calculateDiscount(loyaltyLevel: String) -> Double {
    let discountPercentage =
        if loyaltyLevel == "Gold" { 0.20 }
        else if loyaltyLevel == "Silver" { 0.15 }
        else if loyaltyLevel == "Bronze" { 0.10 }
        else { 0.05 }
    return discountPercentage
}

let customerLoyaltyLevel = "Silver"
let discount = calculateDiscount(loyaltyLevel: customerLoyaltyLevel)
print("Discount Percentage: \(discount * 100)%")  // Prints "Discount Percentage: 15.0%"

In this example:
- The `playerRank()` function takes the number of points a player has scored as input.
- The player’s rank is determined by an if/else expression.
- The value of the chosen branch (e.g., “Gold,” “Silver,” etc.) becomes the value of the `rank` variable.

Benefits and Considerations:

This feature simplifies code by allowing developers to express branching logic more naturally, especially when multiple conditions determine a single value. It eliminates the need for ternary operators, Swift’s definite initialization with assignment on each branch, or even closures.

However, it’s essential to remember that each branch in the if/else expression must be a single expression, and each expression, when type-checked independently, must produce the same type. This ensures clear type checking and makes the code more maintainable.

Conclusion:

The introduction of if/else statements as expressions in Swift 5.9 is a welcome addition that simplifies code and makes it more expressive. It allows developers to use if/else constructs to determine values, making Swift code more concise and readable. This feature, combined with the flexibility of Swift’s type system, enhances the overall development experience.