lesson5.2_rx_notification

Lesson 5.2: NSNotificationCenter.rx_notification

Problem statement

Make an app which:

• Prints "didEnterBackground" to the console when the app is backgrounded.
• Prints "willEnterForeground" to the console when the app is resumed.

Problem project

You can use the project in the problem folder of this repo as a starting point.

Note: I have omitted the Carthage folder from the problem project, because it includes large binary files. In order to use the this project, you will need to run carthage update --platform iOS.

Solution

ViewController.swift:

import UIKit
import RxSwift
import RxCocoa

class ViewController: UIViewController
{
    let disposeBag = DisposeBag()
    
    override func viewDidLoad()
    {
        super.viewDidLoad()
        
        NSNotificationCenter.defaultCenter().rx_notification(UIApplicationDidEnterBackgroundNotification)
            .subscribeNext { (notification) -> Void in
                debugPrint("didEnterBackground")
            }.addDisposableTo(disposeBag)
        
        NSNotificationCenter.defaultCenter().rx_notification(UIApplicationWillEnterForegroundNotification)
            .subscribeNext { (notification) -> Void in
                debugPrint("willEnterForeground")
            }.addDisposableTo(disposeBag)
    }
}

Discussion:

We subscribe to NSNotificationCenter's rx_notification property for the UIApplicationDidEnterBackgroundNotification and UIApplicationWillEnterForegroundNotification notifications.

New concepts to explore

• Open up RxExample.xcodeproj.
  • Take a look at NSNotificationCenter+Rx.swift

Solution project

My solution is included in the solution folder of this repo.

Note: I have omitted the Carthage folder from the solution project, because it includes large binary files. In order to run the this project, you will need to run carthage update --platform iOS.