// NotificationCenterExtensions.swift - Copyright 2024 SwifterSwift
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#if canImport(Foundation)
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import Foundation
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public extension NotificationCenter {
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/// SwifterSwift: Adds a one-time entry to the notification center's dispatch table that includes a notification
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/// queue and a block to add to the queue, and an optional notification name and sender.
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/// - Parameters:
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/// - name: The name of the notification for which to register the observer; that is, only notifications with this
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/// name are used to add the block to the operation queue.
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///
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/// If you pass `nil`, the notification center doesn’t use a notification’s name to decide whether to add the
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/// block to the operation queue.
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/// - obj: The object whose notifications the observer wants to receive; that is, only notifications sent by this
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/// sender are delivered to the observer.
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///
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/// If you pass `nil`, the notification center doesn’t use a notification’s sender to decide whether to deliver
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/// it to the observer.
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/// - queue: The operation queue to which block should be added.
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///
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/// If you pass `nil`, the block is run synchronously on the posting thread.
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/// - block: The block to be executed when the notification is received.
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///
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/// The block is copied by the notification center and (the copy) held until the observer registration is
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/// removed.
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///
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/// The block takes one argument:
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/// - notification: The notification.
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func observeOnce(forName name: NSNotification.Name?,
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object obj: Any? = nil,
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queue: OperationQueue? = nil,
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using block: @escaping (_ notification: Notification) -> Void) {
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var handler: (any NSObjectProtocol)!
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let removeObserver = { [unowned self] in
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self.removeObserver(handler!)
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}
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handler = addObserver(forName: name, object: obj, queue: queue) {
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removeObserver()
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block($0)
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}
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}
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}
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#endif
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