iOS：为推送通知注册设备

Question

My application, upon launch, first registers for push notifications using registerForRemoteNotificationTypes .

I naturally expect either the didRegisterForRemoteNotificationsWithDeviceToken event or the didFailToRegisterForRemoteNotificationsWithError to fire.

But I noticed that if a user has push notifications disabled for my app, then neither one of these get called. Shouldn't it fail in this case and fire didFailToRegisterForRemoteNotificationsWithError ?

The thing is, my app waits for the result of the push registration (whether it passes or fails) before proceeding with the rest of it's networking tasks. I basically rely on the result before doing anything else.

Is there another method I can use to do this? Something like a didFailToRegisterForRemoteNotificationsAsDisabledForApplication (I made this up)??

EDIT:

Apple Docs say the following about registerForRemoteNotificationTypes :

When you send this message, the device initiates the registration process with Apple Push Service. If it succeeds, the app delegate receives a device token in the application:didRegisterForRemoteNotificationsWithDeviceToken: method; if registration doesn't succeed, the delegate is informed via the application:didFailToRegisterForRemoteNotificationsWithError: method. If the app delegate receives a device token, it should connect with its provider and pass it the token.

So if the user's has push notifications disabled for my app and my code is trying to registerForRemoteNotificationTypes why doesn't it fire didFailToRegisterForRemoteNotificationsWithError ?

Answer 1

From Technical Note TN2265 :

No Delegate Callbacks

When the first push-capable app is installed, iOS or OS X attempts to establish a persistent network connection to the push service that will be shared by all push-capable apps on the system. If neither delegate callback application:didRegisterForRemoteNotificationsWithDeviceToken: nor application:didFailToRegisterForRemoteNotificationsWithError: is called, that means that this connection has not yet been established.

This is not necessarily an error condition. The system may not have Internet connectivity at all because it is out of range of any cell towers or Wi-Fi access points, or it may be in airplane mode. Instead of treating this as an error, your app should continue normally, disabling only that functionality that relies on push notifications.

Keep in mind that network availability can change frequently. Once the persistent connection to the push service succeeds, one of the previously-mentioned application delegate methods will be called.

On iOS, push notifications use the cellular data network whenever possible, even if the device is currently using Wi-Fi for other network activity such as web browsing or email. However, the push service will fall back to Wi-Fi if cellular data service isn't available.

If your iOS device is capable of using the cellular data network, check that it has an active cellular data plan. Turn off Wi-Fi in Settings and see if you can still browse the web with Safari, for example. On the other hand, if the push service is using Wi-Fi, any firewalls between your device or computer and the Internet must allow TCP traffic to and from port 5223.

From another section in the same document:

Resetting the Push Notifications Permissions Alert on iOS

The first time a push-enabled app registers for push notifications, iOS asks the user if they wish to receive notifications for that app. Once the user has responded to this alert it is not presented again unless the device is restored or the app has been uninstalled for at least a day.

If you want to simulate a first-time run of your app, you can leave the app uninstalled for a day. You can achieve the latter without actually waiting a day by following these steps:

1. Delete your app from the device.
2. Turn the device off completely and turn it back on.
3. Go to Settings > General > Date & Time and set the date ahead a day or more.
4. Turn the device off completely again and turn it back on.