What Is Payload Data in iOS

What is payload data in iOS?

This is a detail of how Swift implements the Any type. Given that Swift can't know beforehand what you are putting into e.g. front, it needs to store a pointer to that object (in payload_data_0) as well as a pointer to metadata about the stored object's type (in instance_type). As far as I know, payload_data_1 and payload_data_2 are there as an optimization so that Swift can store up to 24-byte large structs in place rather than having to put them in a wrapper object that needs to be stored in a separate heap location.

So, to answer your question: This is neither a bug in Swift, nor an error on your side. Your data gets stored and accessed in the right way. If you would prefer to inspect front more easily while debugging, try

(lldb) po front

in the debugger. Alternatively, change front's type to e.g. UIImage?. If that is not possible, you could declare a protocol

protocol MemoryStoreable: class { }

and extend every type that needs to be stored in those fields like so:

extension UIImage: MemoryStoreable { }

and declare the variable as

var front: MemoryStoreable?

Note that MemoryStoreable is restricted to classes, as otherwise a protocol witness would need to be stored (which is again implemented similarly to the Any field you observed).

Another alternative would be, if you know you'll store e.g. only images and strings in front, to use an enum:

enum MemoryStoreable {
    case `string`(String)
    case image(UIImage)
}

var front: MemoryStoreable?

That will still require at least 25 bytes of storage in your object (possibly 32 due to memory alignment constraints), though, as that's the size of the String struct.

For more details, see e.g. https://mikeash.com/pyblog/friday-qa-2014-08-01-exploring-swift-memory-layout-part-ii.html.

Fetching data from Custom Payload Swift

Parse custom data in notification's userInfo property instead of body. userInfo is a dictionary of custom information associated with the notification.

func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
    let userInfo = response.notification.request.content.userInfo
    if let data = userInfo["data"] as? [String: Any] {
        //
        //Do your parsing here..
    }
}

Issue in getting payload data from notification in iOS

The value for key data is a JSON String, not a dictionary. You have to deserialize it separately

struct NotificationData : Decodable {

    let message : String
    let userImage : URL
    let fromUserId : Int
    let createdDate : String

    private enum CodingKeys: String, CodingKey { case message = "Message", userImage = "UserImage", fromUserId = "FromUserId", createdDate = "CreatedDate" }
}

let delegate = UIApplication.shared.delegate as! AppDelegate
guard let userInfo = delegate.userInfo as? [String:Any],
      let notificationString = userInfo["data"] as? String else { return }
let data = Data(notificationString.utf8)
do {
    let result = try JSONDecoder().decode(NotificationData.self, from: data)
    let message = result.message
    let userImage = result.userImage
    let fromUserId = result.fromUserId
    let createdDate = result.createdDate
} catch { print(error) }

iOS Handle notifications and payload when app is in Background

There are two types of push notifications, alert notifications and background notifications. Alert notifications allow you to deliver visible alerts that can be interacted with in ways that your app can customize.Background notifications allow your application to fetch data from the background, upon receiving push notifications. Background notification should be used to keep your application up to date, even if the application isn't running. Also as of ios 10(and above)instead of using the didReceiveRemoteNotification method you can use didReceive method for handling the alert notifications.

Now coming back to your question in case of the alert notification the didReceive/didReceiveRemoteNotification method is called when the application is in the foreground or when the user taps on the application. Since, you want to update the database you can use the background notifications instead of the alert notification as it will automatically raise your application even when it is in background and will also call the didReceiveRemoteNotification:fetchCompletionHandler. while sending a background push notification make sure you :

• Edit Info.plist and check the "Enable Background Modes" and "Remote notifications" check boxes.
• Add "content-available":1 to your push notification payload, otherwise the app won't be woken if it's in the background
• The notification’s POST request should contain the apns-push-type header field with a value of background, and the apns-priority field with a value of 5.

For more info please refer :
https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server/pushing_background_updates_to_your_app

Access custom push notification payload

You can take the dictionary with

let content = response.notification.request.content.userInfo
if let aps = content["aps"] as? [String: AnyObject] {
    let myValue = aps["my_value"]
    // DO STUFF, in myValue you will find your custom data
}

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