Handle remote notification from within view controller - ios

Question

I am trying to handle remote notifications from within a specific view controller. I've set my app up so a certain view controller is presented with a specific image in an ImageView when I push a remote notification, but I can't change the image without pushing the same controller again. I'm trying to change the ImageView's image from another remote notification once the view controller has been presented. The idea I had for achieving this, is creating a way to handle remote notifications from within the within the file of the view controller that has just been presented, so the remote notification can edit the ImageView's image. This is how I present the view controller in my AppDelegate:
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: #escaping (UIBackgroundFetchResult) -> Void) {
if let data = userInfo["showiMac"] as? [String: String], let iMacConfig = data["iMacConfig"] {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let rootTabBarController = self.window?.rootViewController as! UITabBarController
let firstNavigationController = storyboard.instantiateViewController(withIdentifier: "initialVC1") as! UINavigationController
rootTabBarController.viewControllers![0] = firstNavigationController
//the viewController to present
let viewController = storyboard.instantiateViewController(withIdentifier: "configureiMac") as! ConfigureiMacViewController
// present VC
firstNavigationController.pushViewController(viewController, animated: true, completion: {
viewController.image = UIImage(named: "iMac" + iMacConfig)
})
completionHandler(.noData)
}
}
And here is how image is declared in my view controller:
var image: UIImage!
override func viewDidLoad() {
super.viewDidLoad()
imageView.image = image
}

Answer 1

In your app delegate, do:
weak var configureiMacViewController: ConfigureiMacViewController?
Create helper functions to keep your code clean and readable:
private func updateiMacImage(_ image: UIImage, in existingViewController: ConfigureiMacViewController) {
existingViewController.image = image
}
private func showiMacImage(_ image: UIImage) {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let rootTabBarController = self.window?.rootViewController as! UITabBarController
let firstNavigationController = storyboard.instantiateViewController(withIdentifier: "initialVC1") as! UINavigationController
rootTabBarController.viewControllers![0] = firstNavigationController
//the viewController to present
let viewController = storyboard.instantiateViewController(withIdentifier: "configureiMac") as! ConfigureiMacViewController
configureiMacViewController = viewController
// present VC
firstNavigationController.pushViewController(viewController, animated: true, completion: {
viewController.image = UIImage(named: "iMac" + iMacConfig)
})
}
Then update:
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: #escaping (UIBackgroundFetchResult) -> Void) {
if let data = userInfo["showiMac"] as? [String: String], let iMacConfig = data["iMacConfig"] {
let image = UIImage(named: "iMac" + iMacConfig)
if let existingViewController = configureiMacViewController {
updateiMacImage(image, in: existingViewController)
} else {
showiMacImage(image)
}
completionHandler(.noData)
}
}
The weak var in your AppDelegate will store a reference to your view controller but the "weak" keyword will allow the view controller to be released from memory if it is dismissed, in which case the variable will be nil the next time you try to access it. If the view controller is still visible, then its value will still be defined and you will be able to re-use it to update the image.
You will most likely have to also update your ConfigureiMacViewController code to:
var image: UIImage! {
didSet {
imageView.image = image
}
}
override func viewDidLoad() {
super.viewDidLoad()
imageView.image = image
}
This ensure that if the view controller was already loaded and displayed, but you update the image variable, that the image view is loaded with the most recent image.
Good luck!