Why Are GCM Notifications Not Being Received in iOS Background Mode?

GCM Notifications Not Received in iOS Background Mode

Push notifications sent by GCM may not be received by iOS devices when the app is in the background. This can be attributed to several factors. Here's an analysis of the issue and its resolution:

Problem 1: Notifications Not Received in Background

• GCM notifications are typically delivered as data messages to iOS devices. These messages are not displayed in the notification area unless the app is in the foreground.
• To resolve this, you can modify your PHP script to send push notifications as content-available messages. These messages prioritize delivery even when the app is in the background.

Problem 2: "Could not connect to GCM" Error

• When trying to receive notifications in the background, you receive an error stating "Could not connect to GCM." This error occurs because the GCM service must be running to receive messages.
• Ensure that you have implemented proper connection handling in your AppDelegate.m file, particularly the "applicationDidBecomeActive" and "applicationDidEnterBackground" methods, to establish and maintain a connection to GCM.

PHP Code Solution

Add the following modifications to your PHP script:

<code class="php">$data = array(
    'message' => 'Hello World!',
    'body' => 'Hello World!',
);

$post = array(
    'registration_ids' => $ids,
    'data' => $data,
    'content_available' => true, // To trigger when iOS app is in background
    'priority' => 'high',
    'notification' => $data, // Send notification payload
);</code>

iOS Code Solution

No modifications are required on the iOS side, but ensure you have followed the instructions provided by the GCM documentation to correctly implement the GCM service.

Additional Tips

• Use a push notification testing service to verify that your messages are properly formed and delivered.
• Check if your iOS device has granted permission to receive push notifications.
• If you encounter any other issues, refer to the GCM documentation or seek assistance in the GCM community forums.

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