@propertyWrapper declaration in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an @propertyWrapper in Swift?

An <code>@propertyWrapper</code> is a special structure or class that adds extra behavior to properties, like controlling how values are stored or validated, making code cleaner and reusable.

beginner

How do you declare a property wrapper in Swift?

You declare a property wrapper by creating a struct or class with the <code>@propertyWrapper</code> attribute and defining a <code>wrappedValue</code> property that manages the stored value.

beginner

What is the role of the wrappedValue property inside a property wrapper?

The wrappedValue property holds the actual value of the property and controls how it is accessed and modified when using the wrapper.

intermediate

Can a property wrapper have an initializer? Why?

Yes, a property wrapper can have an initializer to set up initial values or configure behavior when the wrapper is created, allowing customization of how the wrapped property behaves.

beginner

How do you apply a property wrapper to a property in Swift?

You apply a property wrapper by placing its name with @ before the property declaration, like @MyWrapper var myProperty, which automatically uses the wrapper's logic.

What keyword is used to declare a property wrapper in Swift?

A @property

B @propertyWrapper

C @wrapper

D @wrap

The correct keyword to declare a property wrapper is @propertyWrapper.

Which property must a property wrapper define to manage the wrapped value?

A storedValue

B value

C propertyValue

D wrappedValue

The property wrapper must define a wrappedValue property to manage the wrapped value.

How do you apply a property wrapper named Trimmed to a string property?

A @Trimmed var name: String

B var @Trimmed name: String

C var name: @Trimmed String

D Trimmed var name: String

You apply it by writing @Trimmed var name: String before the property.

Can a property wrapper have parameters in its initializer?

A No, initializers are not allowed

B Only default initializers are allowed

C Yes, to customize behavior

D Only static initializers are allowed

Property wrappers can have initializers with parameters to customize how they work.

What happens when you access a property wrapped by a property wrapper?

A The wrapper's <code>wrappedValue</code> getter is called

B The property is accessed directly without wrapper

C The wrapper's initializer runs every time

D The property is copied to a new variable

Accessing the property calls the wrapper's wrappedValue getter to control the value.

Explain how to create and use a simple property wrapper in Swift.

Think about how you add extra behavior to a property.

Describe the purpose of the wrappedValue property inside a property wrapper.

It acts like a gatekeeper for the property's value.