Properties in Swift coding

Here is a link to the Google doc I copied from Apple's documentation for teaching this subject before students take this quiz:

https://docs.google.com/document/d/1PU7b5Y7A7QeeccukmfxwVeyo5z7IM1dyFX-NKbZZLqA/edit?usp=sharing

• I understand

• I don't understand

What is the primary purpose of properties in Swift?

• A. To store values globally.

• B. To associate values with a particular class, structure, or enumeration.

• C. To execute functions inside an instance.

• D. To monitor memory usage of an instance.

Answer explanation

Correct Answer: B
Explanation: Properties associate values with specific instances of a class, structure, or enumeration.

Which types of properties are provided by classes and structures in Swift?

• A. Stored and computed properties.

• B. Computed properties only.

• C. Stored properties only.

• D. None of the above.

Answer explanation

Correct Answer: A
Explanation: Both stored and computed properties are provided by classes and structures.

Can enumerations in Swift have stored properties?

• A. Yes, always.

• B. No, enumerations can only have computed properties.

• C. Yes, but only with property observers.

• D. No, enumerations cannot have properties.

Answer explanation

Correct Answer: B
Explanation: Enumerations in Swift can only have computed properties, not stored ones.

On which types of properties can property observers be added?

• A. Only stored properties defined by the user.

• B. Only computed properties.

• • C. Both stored and computed properties.

• D. Only inherited properties in a subclass.

Answer explanation

Correct Answer: A
Explanation: Property observers can be added to stored properties defined by the user or inherited from a superclass.

What are type properties in Swift?

• • A. Properties that calculate values for specific instances.

• B. Properties shared across all instances of a type.

• • C. Properties that store values for enumerations.

• D. Properties associated with functions.

Answer explanation

Correct Answer: B
Explanation: Type properties are shared by all instances of a type and are associated with the type itself.

What is the primary difference between stored properties and computed properties?

• a) Stored properties calculate their value, while computed properties store it.

• • b) Stored properties store a value, while computed properties calculate it.

• c) Both stored and computed properties are only provided by classes.

• • d) Stored properties and computed properties are always constant.

Answer explanation

Correct Answer: b
Explanation: Stored properties save a constant or variable value, while computed properties dynamically calculate their value using a getter and (optionally) a setter.

Which of the following can define stored properties?

• a) Classes only

• • b) Classes and structures only

• c) Classes, structures, and enumerations

• • d) Enumerations only

Answer explanation

Correct Answer: b
Explanation: Stored properties can be defined by classes and structures, but not by enumerations.

What is the purpose of property observers?

• • a) To calculate the value of a property

• b) To monitor changes to a property’s value and respond with custom actions

• c) To initialize stored properties during instance creation

• d) To enable lazy initialization of properties

Answer explanation

Correct Answer: b
Explanation: Property observers allow you to execute custom code whenever a property’s value changes.

What is the purpose of property wrappers in Swift?

• • A. To compute property values dynamically.

• B. To encapsulate and reuse code in the getter and setter of multiple properties.

• C. To add property observers to computed properties.

• D. To associate constants with a specific type.

Answer explanation

Correct Answer: B
Explanation: Property wrappers allow encapsulating and reusing logic in the getter and setter of multiple properties.