Swift iOS Interview : All about Property and Property Observer

Property : Properties are associated values with a particular class, struct & enum.

Property are basically two types.

1. Stored Property :

Store property can store variable and constant.

Store property given by class & struct.

Store property can’t be define in extension.

2. Computed Property :

Computed property calculate rather than store.

Computed property given by class, struct & enum.

Computed property are always variable.

Computed property provide getter & optional setter

Lazy Stored Property :

A property whose initial value is not calculated till the time of its use.

Lazy stored property is always variable.

Application of Lazy properties : When the initial value for a property is dependent on outside factors whose values are not known until after an instance’s initialization is complete.

class GPS {
     init() {
         print("Initializing GPS...")
     }
 }
 
class Car {
     lazy var navigation = GPS()
 }