What do you mean by Optional Chaining in Swift?

In Swift programming language, Optional Chaining is a process of querying and calling properties. You can chain multiple queries together, but if any link in the chain is nil then, the entire chain fails.

Optional chaining in Swift is a mechanism that allows you to access properties, methods, and subscripts of an optional value, but it will gracefully handle situations where the optional value is nil. It is denoted by placing a question mark (?) after the optional value, and if the optional value is not nil, the property, method, or subscript call will be executed; otherwise, the entire chain will gracefully return nil.

For example, suppose you have an optional variable optionalObject of type OptionalType, and you want to access a property property of optionalObject:

If optionalObject is not nil, property will be accessed, and the result will be of type PropertyType? (another optional). If optionalObject is nil, the entire expression will evaluate to nil.

This mechanism helps avoid runtime errors due to unexpected nil values and allows for more concise and safe code when dealing with optionals in Swift.