Singleton service with many UIViews

问题

Learning swift and just stuck with one issue. I'm trying to use delegates with singleton service.
With delegate i want to update multiple views, but due to singleton implementation delegate keeps last UIView.
So for example i have 3 UIViews with ids 1, 2, 3. When i'll do in init body self.myservice.delegate = self and will try to use specific delegate method ex. myServiceDidUpdate then in this delegate method accessing self.viewId always returning last id.
I guess it's due to singleton service implementation and wanted to ask you for help.

Note: I need singleton implementation to keep specific variable in service

Question: Is that possible to keep 3 instances of my service and also keep variable in that service i need? Or what's the best approach to handle this

Code

class SimpleView: UIView, AudioServiceDelegate {
    private var audioService = AudioService.shared
    var viewId: String?
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.viewId = NSUUID().uuidString
        self.audioService.delegate = self
    }

    func myServiceDidUpdate(identifier: String?) { <-- identifier coming from service i need to keep it across multiple views
        print("SELF", self.viewId) <-- Keeps always last initialized ID
    }
}

MyService

class AudioService {
    static let shared = AudioService()
    var delegate: AudioServiceDelegate?
    var identifier: String?

    ...

    @objc func didUpdate(_ notification: Notification) {
        self.delegate?.myServiceDidUpdate(self.identifier)
    }
}

回答1:

You can keep an array of uids , but the best practice for multi-observer is

// add observer wherever you want to register for new data
notificationCenter.addObserver(self,
                           selector: #selector(self.calledMeth),
                           name: .didReceiveData,
                           object: nil)

//

// post when you want to publish data
NotificationCenter.default.postNotification(name: .didReceiveData, object: nil)

---

extension Notification.Name {
  static let didReceiveData = Notification.Name("didReceiveData")
  static let didCompleteTask = Notification.Name("didCompleteTask")
}

Delegate is used for 1-1 observing while notificationCenter is used for 1-m

来源：https://stackoverflow.com/questions/53547184/singleton-service-with-many-uiviews