Observer Protocol Reference

public protocol Observer<Element>

A protocol representing an observer that can receive elements and a completion signal.

Contract:

onNext(_:) may be called zero or more times.
onComplete() is called at most once, always after all onNext calls.
After onComplete(), no further onNext calls will be made.
onComplete() is NOT called upon external disposal — only on natural upstream termination.

Element
The type of element this observer receives.
Declaration
Swift

associatedtype Element
onNext(_:)
Called when the upstream source emits a new element.
Declaration
Swift

func onNext(_ element: Element)
onComplete()
Called once when the upstream source has terminated. No further onNext calls will follow.
Declaration
Swift

func onComplete()