Каким образом можно реализовать отправку push-уведомлений, включающих изображение?

To send push notifications with images on iOS, a Notification Service Extension is used. It allows intercepting incoming notifications, downloading an image via URL, and adding it to the notification content.

Main steps:

1. Create a Notification Service Extension in the project.
2. In the didReceive(_:withContentHandler:) method of the extension, download the image from the URL provided in the notification payload.
3. Create a UNNotificationAttachment with the downloaded image.
4. Add the attachment to the notification and call the contentHandler.

Example code in Notification Service Extension:

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

    guard let bestAttemptContent = bestAttemptContent,
          let urlString = bestAttemptContent.userInfo["image-url"] as? String,
          let url = URL(string: urlString) else {
        contentHandler(request.content)
        return
    }

    URLSession.shared.downloadTask(with: url) { (location, response, error) in
        if let location = location {
            let tmpDir = FileManager.default.temporaryDirectory
            let tmpFile = tmpDir.appendingPathComponent(url.lastPathComponent)
            try? FileManager.default.moveItem(at: location, to: tmpFile)

            if let attachment = try? UNNotificationAttachment(identifier: "image", url: tmpFile, options: nil) {
                bestAttemptContent.attachments = [attachment]
            }
        }
        contentHandler(bestAttemptContent)
    }.resume()
}

In the push notification payload, add a key with the image URL, for example:

{
  "aps": {
    "alert": "New notification with image"
  },
  "image-url": "https://example.com/image.jpg"
}