Are push notification tokens unique across all app

问题:

I will have multiple applications on the app store and 1 urban airship account to send push notifications to all of these devices. What I want to know is if each Apple device has the same "push token" across all applications? This is more of a database architecture thing so that I don't duplicate a push token many times if one single device uses many of my apps.

If each Apple device generates a unique push token for each application it has installed my architecture needs to change.

回答1:

Device tokens are not exactly unique per device; they're unique per operating system installation. So if a user buys a new device but does not restore from backup, then they'll get a new device token. And if a device is wiped, it will get a new device token, so the new user doesn't get the old user's messages.

In addition, there are different tokens returned for development apps using the sandbox and distribution apps using the production system.

Since a single user might have your app installed on multiple devices legally (iPhone and iPad, for instance), it will be much safer to have a many to many relationship between users and device tokens, to be on the safe side.

And since you mentioned Urban Airship, you might find that our alias feature helps for this sort of thing; you can assign a non-unique alias to the different tokens in our end, and then we'll keep track of the mapping between your users and their device tokens. See the registration and push parts of the UA documentation.

Edit: An update because I saw some more upvotes on this old answer. As of iOS 7, device tokens are unique for each application, even on the same device.

回答2:

According to apple latest doc:

Never cache device tokens in your app; instead, get them from the system when you need them. APNs issues a new device token to your app when certain events happen. The device token is guaranteed to be different, for example, when a user restores a device from a backup, when the user installs your app on a new device, and when the user reinstalls the operating system. Fetching the token, rather than relying on a cache, ensures that you have the current device token needed for your provider to communicate with APNs. When you attempt to fetch a device token but it has not changed, the fetch method returns quickly. For more info check apple doc