How to send push notification when content on a website changes - ios

Question

The core of the app I am building is that it sends a push notification to the user twice a week with a number from a website, at a specific time twice a week (example of the Swift code I'm using for this below).
I did some research about background execution, but I think I will not be able to use it because it's so limited (only for location, limited time, etc.).
Using a server is another option. I do not intend to make money with this app so it has to be a free option. That's why I was looking into Firebase.
I'm learning Swift now, it's the first programming language I'm learning.
Does anyone have an opinion on how to go about doing this?
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let url = URL(string: "https://store.nike.com/be/nl_nl/pd/air-vapormax-flyknit-hardloopschoen-heren/pid-11384993/pgid-12169774")!
let request = NSMutableURLRequest(url: url)
let task = URLSession.shared.dataTask(with: request as URLRequest) {
data, response, error in
var message = ""
if error != nil {
print(error)
} else {
if let unwrappedData = data {
let dataString = NSString(data: unwrappedData, encoding: String.Encoding.utf8.rawValue)
var stringSeperator = "exp-pdp-local-price js-pdpLocalPrice"
if let contentArray = dataString?.components(separatedBy: stringSeperator) {
if contentArray.count > 0 {
stringSeperator = "€"
let newContentArray = contentArray[1].components(separatedBy: stringSeperator)
if newContentArray.count > 0 {
message = newContentArray[0]
print(message)
}
}
}
}
}
if message == "" {
message = "The jackpot couldn't be found. Please try again."
}
DispatchQueue.main.sync(execute: {
//De text in het label van de weer app = message
//Gebruik 'self.' om naar de viewcontroller te verwijzen, want hier zit je in een closure en niet in de viewcontroller zelf.
})
}
task.resume()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 1

Push notifications are not complicated.
Basically you have to register your device to APNS ( Apple push notification system ), once registered device, APNS will return you a token (each token is device unique). When u get the token from APNS you have to send the token to the server which will provide your devices with push notifications. Once the server app receives a token from device, you can save it in database.
For example :
username1 mobile_token1, mobile_token2.
Now, you can get tokens from database for specific username and send push notifications from the server to the devices.
When you send push notifications from server to devices, you have to send the token and data content to APNS, APNS then will send notification to specific device.
So the answer for your question is, if you want to send push notifications you have to send them from backend to devices, the moment you will send push notifications is when the web content changes, you get the tokens from the database, and send notifications to APNS.
The logic is same when you use firebase instead APNS.
Here is a nice tutorial for client side
https://www.raywenderlich.com/156966/push-notifications-tutorial-getting-started

Answer 2

It seems you don't need a push notification (also called remote notification) but a local one (see apple documentation).
You can configure when during week you want this local notification to be fired.
Edit: I did not catch that content of notifications depends on your previous piece of code.
So you can still use a local notification. It will be triggered by what is called a background fetch.
See this tutorial for example (search 'Background fetch' on the page).