For example in Java if I declare a constant inside a class it cannot be modified like the example provided below: ```objective-c public class Product { final String title = ""; public Product(String title){ this.title = title; //this is an error } ```

assigning a value to a constant property when you declare it sets its default value. if the constant is assigned a value during initialization that default value is ignored, and the value assigned in the init method is used instead. from the Swift eBook (https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Initialization.html): You can set the initial value of a stored property from within an initializer, as shown above. Alternatively, specify a default property value as part of the property’s declaration. You specify a default property value by assigning an initial value to the property when it is defined.

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Posted January 3, 2015 1:54am by

Why in the init method we can change title if it is a constant? Inside the class its behavior is like a variable?

For example in Java if I declare a constant inside a class it cannot be modified like the example provided below:

public class Product {

     final String title = "";

    public Product(String title){
        this.title = title; //this is an error

    }

1 Answer

January 3, 2015 2:42am

assigning a value to a constant property when you declare it sets its default value. if the constant is assigned a value during initialization that default value is ignored, and the value assigned in the init method is used instead.

from the Swift eBook:

You can set the initial value of a stored property from within an initializer, as shown above. Alternatively, specify a default property value as part of the property’s declaration. You specify a default property value by assigning an initial value to the property when it is defined.

January 3, 2015 2:58am

The constructor actually overrules the constant altogether, see the below example which functions perfectly fine in Xcode 6.1.1.

class Product {
    let title: String = "[Unknown]"
    let price: Double = 99.0

    init(title: String, price: Double) {
        self.title = title
        self.price = price
    }
}

let tv = Product(title: "Samsung Smart TV", price: 10000.00)

January 3, 2015 3:05am

good catch, edited my initial post. looks like the values assigned at declaration are just default values that only stick if the property is not assigned a value in init

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Juan Cabral

Juan Cabral

Why in the init method we can change title if it is a constant? Inside the class its behavior is like a variable?

1 Answer

Stone Preston

Stone Preston

Chris Shaw

Chris Shaw

Stone Preston

Stone Preston