Handling where the user goes when clicking on a notification? - ios

Question

I have several different types of notifications, all of which should take the user to a different view controller when the notification is clicked on.
How should this be handled (I'm using Swift 5, by the way)? From my research, I see that people tend to present a new view controller in the AppDelegate's didReceive function, but doing all the logic, for several different view controllers, all in the AppDelegate seems wrong. Is this really the right way of doing it?
Further, I'm using Firebase to send messages to the device from the backend. I have a separate class, FirebaseUtils, where I handle all logic for the data that's passed along. Would it be better to present the view controller from here? If so, how would I do that without the root view controller?

Answer 1

I typically set up something along these lines (untested):
Create a NotificationHandler protocol for things that may handle notifications
protocol NotificationHandler {
static func canHandle(notification: [AnyHashable : Any])
static func handle(notification: [AnyHashable : Any], completionHandler: #escaping (UIBackgroundFetchResult) -> Void)
}
Create a notificationHandlers variable in AppDelegate and populate it with things that may want to handle notifications.
let notificationHandlers = [SomeHandler.self, OtherHandler.self]
In didReceive, loop over the handlers, ask each one if it can handle the notification, and if it can, then tell it to do so.
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: #escaping (UIBackgroundFetchResult) -> Void) {
guard let handler = notificationHandlers.first(where:
{ $0.canHandle(notification: userInfo) }) {
else {
return
}
handler.handle(notification: userInfo, completionHandler: completionHandler)
}
This approach keeps the logic out of the AppDelegate, which is correct, and keeps other types from poking around inside the AppDelegate, which is also correct.

Answer 2

would something like this work for you?
struct NotificationPresenter {
func present(notification: [AnyHashable: Any], from viewController: UIViewController) {
let notificationViewController: UIViewController
// decide what type of view controller to show and set it up
viewController.present(notificationViewController, animated: true, completion: nil)
}
}
extension UIViewController {
static func topViewController(_ parentViewController: UIViewController? = nil) -> UIViewController {
guard let parentViewController = parentViewController else {
return topController(UIApplication.shared.keyWindow!.rootViewController!)
}
return parentViewController.presentedViewController ?? parentViewController
}
}
let notificationPresenter = NotificationPresenter()
func application(_ application: UIApplication,
didReceiveRemoteNotification userInfo: [AnyHashable: Any],
fetchCompletionHandler completionHandler: #escaping (UIBackgroundFetchResult) -> Void) {
notificationPresenter.present(userInfo, from: UIViewController.topViewController())
}