What makes a property a computed property in Swift

Question

Let\'s started with the code snippet:

St Foo {
    var proA: Int = 0 { // needs initialization
        willSet {
            print(\"about to set proA to \\(         


        

Answer 1

A stored property is a property of which the property value is stored together with the instance of the class or struct. The value may be changed, but the property can also be a constant. Thus a stored property can be as simple as:

var proA: Int
let proB: Int
var proC: Int = 0

Computed properties do not store a value. Thus you cannot assign a value to a computed property. A Computed property should have a getter that returns a value. I a broad term, you can think of a computed property as a property that returns the value of a function.

Example of Computed Property

var proA: Int {
    return proB * proC
}

With regards to your questions:

1. Computed Property is therefor a property that do not store a value, and contains a get to return the 'computed' value of the property.
2. a is correct, b computed properties should not have initialization, c if you mean willSet and didSet. Yes they are like observers for when the property's value will change and did change respectively
3. Since the value of a computed property is not stored and will never be used, the compiler forbids it.

Hope this helps a bit.