Optional chaining
Optional chaining is a process to query and call properties, methods, and subscripts on an optional that may currently be nil. Optional chaining in Swift is similar to messaging nil in Objective-C but in a way that works for any type and can be checked for success or failure.
The following example presents two different classes. One of the classes, Person, has a property of type of Optional (residence), which wraps the other class type Residence:
class Residence {
var numberOfRooms = 1
}
class Person {
var residence: Residence?
} We will create an instance of the Person class, sangeeth:
let residence = Residence() residence.numberOfRooms = 5 let sangeeth = Person() sangeeth.residence = residence
To check for numberOfRooms, we need to use the residence property of the Person class, which is an optional. Optional chaining enables us to go through Optionals as follows:
if let roomCount = sangeeth.residence?.numberOfRooms {
// Use the roomCount
print...
