I'm making an iphone app that uses NSURLConnection to download some data from the web. I need to store this data somewhere, so my app can send out push notifications when the data changes in a particular way. For example, the data being stored is a number and a push notification will be sent out when that number changes by +-10.
I'm new to this, so I'm probably overcomplicating how I think this can be accomplished. I'm thinking I need to create a database and some server-side code that continuously pulls the data. When the data changes to my specifications (ex. +-10), it somehow pushes the data to the app which then sends out a push notification.
Is there an easier way to accomplish staying within xcode dev?
The app doesn't send the push notification. The point of push notifications is your app can be in the background so it can't poll/check for a given condition (like your +-10).
When that interesting even happens server side, it can push a notification to the device. The device can handle that notification by (1) showing text (2) playing a sound or (3) updating a badge on an icon.
So, it's not about your device downloading the data into database (although that has value for offline and occasionally connected scenarios).
So, you'll need a server side component that detects that +-10 change (on data change or polling) and then sends the push to the device. Now, it's possible that devices are sending data to your service (uploading) and when and interesting event happens it could notify other instances of the app.
This link may help clarify push notifications: http://www.raywenderlich.com/3443/apple-push-notification-services-tutorial-part-12
Related
Consider this scenario:
1) Launch the app
2) Put the app in background (pressing Home button)
3) Server send a PUSH notification to client
4) The user resume the app clicking on its icon from menu
In this case didReceiveRemoteNotification and didFinishLaunchingWithOptions are not called, so how do I get notifications ?
Simple answer: In this scenario you cannot get it.
If the push notification contains important payload then it should not contain it because you should not rely on it for anything important because:
notifications are not guaranteed to be delivered to the device in the first place
the user can turn off notifications
they could ignore them
if the device is turned off when it is due to be displayed then it will be lost
If you need to know if the server has sent a notification then make a connection home when you become active and ask it if it did so.
You should check in the applicationWillEnterForeground: method.
I think the app will not see anything if the user chooses to ignore the push notification. The workaround that comes into mind first would be to offer a way of checking the server if anything worth a push notification has happened since the last time the app was opened and correlating that with the local data.
I think the idea behind this system is to separate actual functionality from push notifications and making sure the notifications are used for only one purpose - notifying of new data/event/etc, thus leaving the downloading and processing of data to the app once it's fully in the foreground. I.e everything should be duplicated in the launching sequence to make sure the app is always up-to-date, even if the notifications during downtime were not received/ignored.
application:didReceiveRemoteNotification: is therefore meant for not transferring the data and updating the model, but reacting to the event and starting the necessary procedures. Although most of the time, the data may be so small that it fits in the notification and therefore the application can proceed without downloading any further content.
I'm wondering if there is any way of retrieving the last-received push notification if the app is launched from the home screen instead of by pressing the 'View' button on the notification.
The app we're writing is for dealing with sensitive data, and it's important to be able for the central server to be able to remotely disable a client at will, without having the requirement that the app needs an internet connection to launch.
The basic idea I came up for this would be to send a push notification with a custom payload letting the app know to disable itself until it can properly sync its data.
This would work if the user pressed View on the notification, but not if they cancelled it and then launched the app separately.
I'd love to know if this is possible, or otherwise if there's a better way to implement this functionality.
It's not possible. Your app would have to connect to the server on launch and get its latest status from there. If your use case is that sensitive, push notifications are probably not reliable enough anyway because Apple does not guarantee that a push notification will actually be delivered.
Like Ole said, not possible.
Note that you shouldn't be relying on push notifications for anything like this. From Apple's push notifications programming guide:
Remember that delivery of notifications is “best effort” and is not guaranteed.
i m making an application where data is accesed from website and displayed with an application.i have made an action which will tell the user that new data has arrived.this will work properly if the application is open .but if the application is closed than ,is there any way to tell the user that new data has arrived ,,so that he can open the application and check the data?
If you are using the Apple Push Notification Service (APNs), your messages will be delivered whether the application is running or not. For information on how to control what information is presented to the user, read the Apple Push Notification Programming Guide.
You should use Apple Push Notification Service, like codelark said.
I would recommend looking into Urban Airship for help getting started. It's a third party service, but it makes things much easier. Urban Airship does have their own tutorials and code samples which may be easier than Apple's.
As a follow up to the reference to apple push notification, as of ios4.0 I believe you, you may have a few more options, 1) you can send local notifications (just like push notifications, but they originate from inside your app) that could be timed to be delivered even if the app is not running..assuming you know approximately how long it will take for data to arrive. 2) if your data update will occur soon after the app closed.. your app can request a certain amount of time to complete an operation (even though the user has closed the app) and wait for the data, then send a local notification to tell the person to come back into the app. 3) if your functions based on gps updates, music streaming, or voip you can set a flag so your app continues to run in the background
sorry for the unstructuredness of the answer, this was just off the top of my head, hope it helps
How are push notification better than pull notification on iPhones?
Are there any links with more information about this?
Any help would be appreciated.
Pull notification requires the user to be running your app, and your app to be wasting battery power constantly polling some server (or waiting on some network socket in another thread , or using the new background services).
Push notifications, when enabled by the user, and if the phone has a network connection, allows a message to be sent to a phone even when it's not running your app, prompting the user that your app wants some attention. It uses a much lower power network connection than any frequent polling method.
If you want to know about push notifications, I'm guessing you are interested in the Apple Push Notification Service.
You can read about its architecture here:
http://developer.apple.com/iphone/library/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/ApplePushService/ApplePushService.html
There is no such thing as a "pull" notification, but using APNs gives you the advantage that you don't have to manually poll a server every so often within an app, which usually saves you a lot of battery life in the long run if you are interested in telling the user about sporadic, infrequent events. Using push notifications also allows you to interrupt the user if they are not currently running your app, which of course can be very useful in certain use cases.
You should think about what kind of message flow you expect to see between your app and any server components in your system. Push notifications make the most sense where some event external to your app is going on which requires the app to be updated in some way, and where the frequency of those updates is low or highly variable.
i wish to PUSH an XML File from a windows PC to the iPad,
how and what should i do so that the app can "listen" for events like that.
See the Local and Push Notification Programming Guide.
You can only use push notifications to play alerts, display a message, or badge the application icon.
Anything more, and you have to take the client/server approach where the the apps must be running on both ends. A mix is usually best. Push a notification of something, which in turn can fire up the client, which in turn can download the latest chunk if structured information in XML (or whatever) form.