1、ios-push-notifications
https://parse.com/tutorials/ios-push-notifications
2、iOS8推送消息的快速回復處理
http://blog.csdn.net/yujianxiang666/article/details/35260135
3、iOS8註冊通知
http://blog.csdn.net/apple_app/article/details/39228221
4、Device token的獲得和改變詳解
Device token for an iPhone device生成之後就永遠不變嗎？
不是，if a device is wiped (應該是重裝系統), it will get a new device token.
官方網站是這樣寫的： If the user restores backup data to a new device or computer, or reinstalls the operating system, the device token changes
正是因爲device有可能改變，所以建議在app start時（即在didFinishLaunchingWithOptions 裏）調用registerForRemoteNotificationTypes來獲取device token以檢查device token是否改變，如果改變了就應該把新token傳給push provider。（官方描述：An application should register every time it launches and give its provider the current token）
device token應該存儲在NSUserDefaults來達到新舊比較的目的
那麼舊device token在push provider對應的record怎麼辦？
方案1：把舊device token send to provider and request delete record
方案2：使用apns feedback service。
方案2可能更好些，因爲總是需要使用apns feedback service來處理用戶在device裏刪除app的情況。
調用registerForRemoteNotificationTypes方法後，成功註冊後，APNS就會返回一個device token，然後回調delegate methoddidRegisterForRemoteNotificationsWithDeviceToken, 如果註冊失敗，則回調delegate method didFailToRegisterForRemoteNotificationsWithError。
注意：
* 在第一次調用registerForRemoteNotificationTypes方法時沒有聯網，則既不會調用didRegisterForRemoteNotificationsWithDeviceToken，也不會調用didFailToRegisterForRemoteNotificationsWithError
*在第一次調用registerForRemoteNotificationTypes註冊成功後，之後即使沒有聯網，再調用registerForRemoteNotificationTypes時都會以最上一次的device token作爲參數回調didRegisterForRemoteNotificationsWithDeviceToken方法。
* (官方描述) If your application has previously registered, calling registerForRemoteNotificationTypes: results
in the operating system passing the device token to the delegate immediately without incurring additional overhead.
上述東東參考官方網站關於Registering for Remote Notifications的講解