Is it possible to cancel a pushed notification before displaying it on the users phone ?

I have some custom logic which decides whether a notification needs to be displayed/appear . Is it possible for me to control this behaviour from the client side ios/android code ?

CodePudding user response：

Once a message is sent to Firebase Cloud Message, there is no way to cancel its delivery.

If your message contains only a data element and no notification, displaying the message is handled by your application code - so in that case you may be able to suppress its display there.

CodePudding user response：

Although the best way is to handle this is to cancel it on backend side, you still can add UNNotificationServiceExtension and override the didReceive method:

override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
    self.receivedRequest = request;
    self.contentHandler = contentHandler
    self.content = (request.content.mutableCopy() as? UNMutableNotificationContent)
    

    if let content = self.content {
        // I had to check something inside the push itself
        if let infoDictionary = content.userInfo {
            // Check something inside the push notification
            contentHandler(content)
            return
        }
    }
    // Otherwise, send an empty notification to the system and it will show nothing
    contentHandler(UNNotificationContent())
}