Search code examples
iosswiftswift3nsnotificationcenternotificationcenter

NotificationCenter swift3 Can't observe post


I have 3 notifications:

NotificationCenter.default.post(name:NSNotification.Name("Notification1"), object: nil)
NotificationCenter.default.post(name:NSNotification.Name("Notification2"), object: nil)
NotificationCenter.default.post(name:NSNotification.Name("Notification3"), object: nil)

And I have for each post one differents observer in view controller

First:NotificationCenter.default.addObserver(forName:NSNotification.Name("Notification1"), object: nil, queue: nil, using: updateUx)

Second:NotificationCenter.default.addObserver(forName:NSNotification.Name("Notification2"), object: nil, queue: nil, using: updateUx)

Third:NotificationCenter.default.addObserver(forName:NSNotification.Name("Notification3"), object: nil, queue: nil, using: updateUx)

updateUx func contain only a print of notification.

I only got my first notification I cannot catch the two other, I don't know why.


Solution

  • Add your observers like following:

    NotificationCenter.default.addObserver(self, selector: #selector(updateUx), name: NSNotification.Name("Notification1"), object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(updateUx), name: NSNotification.Name("Notification2"), object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(updateUx), name: NSNotification.Name("Notification3"), object: nil)
    

    And you are good to go.


    EDIT: Full source code (This project has a UIButton on view and the @IBAction is connected to it in storyboard. On tapping that button, all 3 notifications will get posted. The log is supposed to get printed thrice in console)

    class ViewController: UIViewController {
    
        override func viewWillAppear(_ animated: Bool) {
            super.viewWillAppear(animated)
            NotificationCenter.default.addObserver(self, selector: #selector(updateUx), name: NSNotification.Name("Notification1"), object: nil)
            NotificationCenter.default.addObserver(self, selector: #selector(updateUx), name: NSNotification.Name("Notification2"), object: nil)
            NotificationCenter.default.addObserver(self, selector: #selector(updateUx), name: NSNotification.Name("Notification3"), object: nil)
        }
    
        override func viewWillDisappear(_ animated: Bool) {
            super.viewWillDisappear(animated)
            NotificationCenter.default.removeObserver(self)
        }
    
        @IBAction func abc (_ sender: UIButton) {
            NotificationCenter.default.post(name:NSNotification.Name("Notification1"), object: nil)
            NotificationCenter.default.post(name:NSNotification.Name("Notification2"), object: nil)
            NotificationCenter.default.post(name:NSNotification.Name("Notification3"), object: nil)
        }
    
        func updateUx(){
            print("received...")
        }
    }