TestLaunch

1. demonstrate the operation of a NetworkMonitor

class NetworkMonitor uses NWPathMonitor() from Apple's Network kit.

NetworkMonitor is a singleton, providing the isConnected status to any of the app's view controllers.

NetworkMonitor.shared usage in a ViewController:

get the current state when you need it

print(NetworkMonitor.shared.connected ? "is connected" : "is disconnected"

add a handler to get a notification when the connectivity changed

     NetworkMonitor.shared.handler = { isConnected in
         print(isConnected ? "is connected" : "is disconnected")
     }

if the handler references the view controller's self, it must declare [weak self] to avoid memory retention cycles

     NetworkMonitor.shared.handler = { [weak self] isConnected in
         DispatchQueue.main.async {
             self?.connectedLabel.text = isConnected ? "connected" : "disconnected"
         }
     }

What Is a Singleton and How To Create One In Swift

Weak self and unowned self explained in Swift

Notes:

The app consists of several ViewControllers which use Show segues to present siblings and unwind segues to return to the controller that presented them. The app contains a NetworkMonitor.shared which runs its monitoring while the app is running.
The app may go into the background and later come back from background.
Each ViewController shall have a Network StatusLabel just underneath the Status Bar. StatusLabel shall be invisible (hidden) whenever the device is connected to the internet, and visible with text "∆ No Network" when disconnected.

StatusLabel shall be updated or kept up to date: 3.1 when a presented ViewController appears on the screen (hiding the presenting VC) 3.2 when a presented ViewController disappears from the screen (unhiding the presenting VC) 3.3 when the connectivity changes 3.4 when the app comes back from the background

Current concepts and principles:

NetworkMonitor.shared is static, therefore it is initialized on the first access after the app start.
NetworkMonitor monitors the network connection status until the app exits.
ViewControllers wishing to display the connection status must install a handler.
NetworkMonitor will call the handler upon its installation and when the connection status changes.
Only one client's handler can be instaled at a time.

rudifa/iOS-TestLaunch

TestLaunch

1. demonstrate the operation of a NetworkMonitor