TypedNotification

A type-safe way to receive notifications.

This library is inspired by

• Typed Message pattern described in Pattern Hatching: Design Patterns Applied, Chapter 4
• Disposable pattern
• C# event delegate += syntax.

With this library, it is able to register notification handlers that will receive type-safe information without writing boilerplate codes to decode notification userInfo object.

Get Started

Installation

Current, this library only supports Swift Package Manager. In Package.swift, add the following into dependencies array:

.package(url: "https://github.com/dbi1463/typed-notification.git", .branch("master"))

Next, add TypedNotification to your targets dependencies like:

.target(
    name: "[your target]",
    dependencies: [ "TypedNotification" ]
),

Register an observer

To receive a type-safe notification is easy. All supported notifications are listed in Notifications. For example, to receive a keyboard will show notification, use the add operator (+) to subscribe the Notifications.keyboard.willShow notification.

let subscription = Notifications.keyboard.willShow + { [weak self] info in
    // info is a KeyboardInfo struct, can access the beginFrame, endFram, animation duration,
    // and animation curve like:
    // info.beginFrame, info.endFrame, ...
}

The registered handler will be invoked before the keyboard trying to show, and the information has been decoded as KeyboardInfo and pass to the handler. Note that the returned subscription should be kept, and in the closure, to access self, remember to add [weak self] to avoid reference cycle.

Remove the observer

The returned subscription is a disposable object that will remove notification observer for you when itself has been deallocated. Thus, the only thing to do is to keep the subscription object as member data in the view controller (or the object that handles the notification). When the view controller disappeared (dellocated), the subscription will remove the observer automatically.

License

TypedNotification is released under the MIT license. See LICENSE for details.