Notification Center Observer protocol

NotificationObserverProtocol.swift

/// Reflects notification observer functionality of `NotificationCenter`.
public protocol NotificationObserverProtocol: AnyObject {
    /// Adds an entry to the notification center to call the provided selector with the notification.
    /// - Parameters:
    ///   - observer: An object to register as an observer.
    ///   - aSelector: A selector that specifies the message the receiver sends observer to alert it to the notification
    ///     posting. The method that aSelector specifies must have one and only one argument
    ///     (an instance of NSNotification).
    ///   - aName: The name of the notification to register for delivery to the observer. Specify a notification name to
    ///     deliver only entries with this notification name.
    ///     When nil, the sender doesn’t use notification names as criteria for the delivery.
    ///   - anObject: The object that sends notifications to the observer. Specify a notification sender to deliver only
    ///     notifications from this sender.
    ///     When nil, the notification center doesn’t use sender names as criteria for delivery.
    func addObserver(
        _ observer: Any,
        selector aSelector: Selector,
        name aName: NSNotification.Name?,
        object anObject: Any?
    )
}

public extension NotificationObserverProtocol {
    /// Adds an entry to the notification center to call the provided selector with the notification.
    /// - Parameters:
    ///   - observer: An object to register as an observer.
    ///   - aSelector: A selector that specifies the message the receiver sends observer to alert it to the notification
    ///     posting. The method that aSelector specifies must have one and only one argument
    ///     (an instance of NSNotification).
    ///   - aName: The name of the notification to register for delivery to the observer. Specify a notification name to
    ///     deliver only entries with this notification name.
    ///     When nil, the sender doesn’t use notification names as criteria for the delivery.
    func addObserver(
        _ observer: Any,
        selector aSelector: Selector,
        name aName: NSNotification.Name?
    ) {
        addObserver(observer, selector: aSelector, name: aName, object: nil)
    }
}

extension NotificationCenter: NotificationObserverProtocol {}