app is sending multiple notifications - ios

Question

I want my app to send a single notification at a given time and repeat daily. The notification sends fine but it sends multiple notifications. So instead of sending 1, it sends 5. How can I fix this with code. I have 2 viewcontrollers if that is meaningful.
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
// ask for permission for notifications
UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound], completionHandler: {didAllow, error in
})
// making the content of the notification
let center = UNUserNotificationCenter.current()
let content = UNMutableNotificationContent()
content.title = "Get Motivated"
content.body = "Need Some Motivation? We've Got Plenty!"
content.sound = UNNotificationSound.default()
//triggering notification
var dateComponents = DateComponents()
dateComponents.hour = 13
dateComponents.minute = 35
let trigger = UNCalendarNotificationTrigger(dateMatching: dateComponents, repeats: true)
let request = UNNotificationRequest(identifier: UUID().uuidString, content: content, trigger: trigger)
center.add(request)

Answer 1

It's a little hard to be precise without seeing more of your code so forgive me if I misunderstood something. Nevertheless, here are some suggestions:
You are sending notifications every time your view controller's "viewDidLoad" method is called. For a bit of context, in earlier versions of iOS, in order to save memory, views were unloaded from memory when views were removed from view hierarchy (say, after a transition to a different full screen view); it is not done anymore, but "viewDidLoad" is not guaranteed to be called only once during the life time of a given view controller. In addition to that, if you instantiate and present a view controller of this class more than once, "viewDidLoad" will be called multiple times.
Your code, also, does not seem to take into account a possibility that the app might be launched more than once.
In order to ensure that only one notification is scheduled, you can:
Check for already scheduled notifications and see if the one you are trying to add is a duplicate (you can use UNUserNotificationCenter.getPendingNotificationRequestsWithCompletionHandler method for that);
Remove all already scheduled notifications and add new ones in their place (see UNUserNotificationCenter.removeAllPendingNotificationRequests).
The method you choose, of course, depends on the logic of your app.
Good luck!