Noted

A minimalistic and effective replacement for NSNotificationCenter, that promotes the observer pattern and keeps weak references to it’s observers.

Features:

Simple Setup
Use enum As Notification
Weak References
No Unregister Necessary
OSS, Free, Maintained, No Dependencies

📝 Requirements

iOS 8.0+
Swift 3.0+

📦 Installation

Carthage

# Swift 3
github "nodes-ios/Noted" ~> 2.0

# Swift 2
github "nodes-ios/Noted" ~> 1.0

💻 Usage

Noted itself is a singleton that you can access from anywhere in your app, and might be especially useful for easily sending messages to your router and/or any other class.

Start with:

import Noted

Protocols

There are two protocols you need to implement in order for Noted to work. One for the notification (object/structure/enum) a.k.a Note and second for each observer you want to add.

Note Type

Just make your object conform to it and that’s it!

We recommend using enums as you get most out of Swift and you can associate values without wrapping them in some ugly dictionary with string keys.

enum Note: NoteType {
    case ShowLoginFlow
    case SignupForPush(userId: Int)
}

Note Observer

The observer protocol requires you to implement a function didReceive(note: NoteType) that will be called each time a notification is sent and your observer is add as and observer.

NOTE: This function will be executed on the main thread.

class ViewController: UIViewController, NoteObserver {
    // MARK: - Note Observer -
    func didReceive(note: NoteType) {
        switch note {
        case .SingupForPush(let userId):
            print(userId)
        }
    }
}

Actions

There are three actions Noted supports:

Add Observer
Remove Observer*
Post Note

*All observers have a weak reference in Noted, so you are not required to manually remove observers if you want them to disappear on deinit.

Adding Observer

func viewDidLoad() {
    super.viewDidLoad()
    Noted.defaultInstance.add(observer: self)
}

NOTE: You need to keep a strong reference to the observer, otherwise it will get removed immediately after adding.

Removing Observer

func viewWillDisappear() {
    super.viewWillDisappear()
    Noted.defaultInstance.remove(observer: self)
}

Posting Notes

Posting notes is as simple as it could get, simply call post(note: note) and it will be send momentarily.

func buttonPressed() {
    Noted.defaultInstance.post(note: Note.SignupForPush(userId: 1))
}

NOTE: Be advised that Noted uses a background thread and synchronizes post action with addition and removal of observers.

Advanced Features

If you send a lot of notifications and have many observers, this section might be useful for you.

Filtering

Noted offers an option to filter which observers will receive a notification and by default uses a PassthroughNoteFilter that let’s all notifications come through.

You can override this behaviour by providing your own NoteFilter on the observer.

struct RandomFilter: NoteFilter {
    func shouldFilter(note: NoteType) -> Bool {
        return arc4random() % 10 < 5
    }
}

class TestObserver: NoteObserver {
    let noteFilter: NoteFilter = RandomFilter()

    func didReceive(note: NoteType) { }
}

NOTE: Do not use the filter provided above unless you have #courage.

👥 Credits

Made with ❤️ at Nodes.

📄 License

Noted is available under the MIT license. See the LICENSE file for more info.