Grammar Agreement in Swift

Swift provides a powerful feature to handle grammar agreement automatically using localized attributed strings. This feature ensures that your strings are grammatically correct based on the context, such as changing words from singular to plural based on a count value. Here's how you can use this feature in a real-time example.

1. Introduction to Grammar Agreement

Grammar agreement ensures that your strings are grammatically correct based on context. For example, "1 apple" should change to "2 apples" when the count increases. This can be achieved using localized attributed strings in Swift.

2. Real-Time Example: Shopping Cart Item Count

Consider a scenario where you have a shopping cart in an e-commerce app that displays the number of items a user has added. You want to ensure that the item names are correctly inflected based on the count.

Scenario: Displaying Item Count

import Foundation

struct ShoppingCart {
    var itemCount: Int
    
    func itemDescription() -> String {
        return String(AttributedString(
            localized: "You have ^[\(itemCount) \("item")](inflect: true) in your cart."
        ).characters)
    }
}

// Example usage:

var cart = ShoppingCart(itemCount: 1)
print(cart.itemDescription())  // Output: "You have 1 item in your cart."

cart.itemCount = 2
print(cart.itemDescription())  // Output: "You have 2 items in your cart."        

In this example:

• Localized Attributed String: We create an AttributedString using the localized constructor.
• Markdown Syntax: The special syntax ^[\(itemCount) \("item")](inflect: true) indicates the inflected region.
• String Interpolation: The count (itemCount) and the noun ("item") are included in the square brackets.
• Inflection: The inflect: true attribute tells Swift to inflect the noun based on the count.

3. How It Works

• Attributed String Requirement: You must use an attributed string declared as localized to access the grammar agreement feature.
• Markdown Usage: Use Apple’s custom Markdown attribute syntax within the attributed string.
• String Interpolation: Include the relevant variables (count and noun) in the string interpolation within the square brackets.
• Literal String: Ensure the string is a literal and typed as a String.LocalizationValue.

4. Detailed Breakdown

import Foundation

struct ShoppingCart {
    var itemCount: Int
    
    func itemDescription() -> String {
        // Create a localized attributed string with inflection
        let attributedString = AttributedString(
            localized: "You have ^[\(itemCount) \("item")](inflect: true) in your cart."
        )
        // Convert the attributed string to a standard string
        return String(attributedString.characters)
    }
}

// Example usage with different item counts:

var cart = ShoppingCart(itemCount: 1)
print(cart.itemDescription())  // Output: "You have 1 item in your cart."

cart.itemCount = 2
print(cart.itemDescription())  // Output: "You have 2 items in your cart."

cart.itemCount = 5
print(cart.itemDescription())  // Output: "You have 5 items in your cart."        

Here’s what you need to remember:

• Literal String: Use a string literal to get special interpolation rules.
• Localization Value: The string should be typed as String.LocalizationValue for the interpolation and inflection to work.

5. Conclusion

Using localized attributed strings in Swift, you can automatically handle grammar agreement for singular and plural forms based on context. This makes your code cleaner and reduces the need for manual string manipulation. By following the examples provided, you can integrate this feature into your Swift applications to ensure grammatical accuracy effortlessly.