Add support for notification priority and the iOS 13 `apns-push-type` header field.

`apns-push-type` will be `alert` if the body of the notification is set, otherwise it will be `background`.

apnsframework/APNS.php

@@ -84,6 +84,8 @@ class APNS {
 		$header[] = "content-type: application/json";
 		$header[] = "authorization: bearer {$authorization}";
 		$header[] = "apns-topic: {$this->bundleId}";
+		$header[] = "apns-push-type: " . ($notification->getBody() != null ? "alert" : "background");
+		$header[] = "apns-priority: " . $notification->getPriority();
 
 		// Create the curl request.
 		$ch = curl_init($token->getTokenUrl());

apnsframework/APNSNotification.php

@@ -97,6 +97,18 @@ class APNSNotification {
 	 */
 	private $isMutable = false;
 
+	/**
+	 * The priority of the notification.
+	 * Specify 10 to send the notification immediately. A value of 10 is appropriate for notifications that trigger an
+	 * alert, play a sound, or badge the app’s icon. It's an error to specify this priority for a notification whose
+	 * payload contains the content-available key.
+	 * Specify 5 to send the notification based on power considerations on the user’s device. Use this priority for
+	 * notifications whose payload includes the `content-available` key. Notifications with this priority might be
+	 * grouped and delivered in bursts to the user’s device. They may also be throttled, and in some cases not delivered.
+	 * @var int
+	 */
+	private $priority = 10;
+
 	public function generateJSONPayload(): string {
 		$payload = array();
 
@@ -373,4 +385,34 @@ class APNSNotification {
 		$this->isMutable = $isMutable;
 	}
 
+	/**
+	 * The priority of the notification.
+	 * Use 10 to send the notification immediately.
+	 * Use 5 to send the notification based on power considerations on the user’s device.
+	 * Is 10 by default.
+	 * @return int
+	 */
+	public function getPriority(): int {
+		return $this->priority;
+	}
+
+	/**
+	 * The priority of the notification.
+	 * Specify 10 to send the notification immediately. A value of 10 is appropriate for notifications that trigger an
+	 * alert, play a sound, or badge the app’s icon. It's an error to specify this priority for a notification whose
+	 * payload contains the content-available key.
+	 * Specify 5 to send the notification based on power considerations on the user’s device. Use this priority for
+	 * notifications whose payload includes the `content-available` key. Notifications with this priority might be
+	 * grouped and delivered in bursts to the user’s device. They may also be throttled, and in some cases not delivered.
+	 * Only 10 or 5 are allowed. Other values will throw an exception.
+	 * @param int $priority
+	 * @throws APNSException Throws when priority is a value that is different from 5 or 10.
+	 */
+	public function setPriority(int $priority): void {
+		if($priority != 5 && $priority != 10) {
+			throw new APNSException("Only values 5 and 10 are allowed to be set as priority.");
+		}
+		$this->priority = $priority;
+	}
+
 }
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