asynchronous request objective c

hi i am developing a sms App for my client. so far i have put down this plan in place.

1)The app keeps polling the server with an asynchronous request so that it does not interfere with the user interface.

2) for sending sms i am currently using synchronous request , depending on the reply from server i have do various things. i am showing the spinning circle and make the user wait until i get the respons开发者_如何学编程e from server.

my client has problem with point 2.

The client says as soon as the send sms button is clicked it has to go back to the homescreen and should be able to navigate to any screen and do all other things that the app offers. i could have used async request , but i am not sure how to handle the responses from the server when i am on different view controller other than the one request is called from.

Can somebody help me on this.

Thank You.

The classic way of handling the response of an asynchronous action is either using delegation or notifications. Do not use a singleton. This breaks modularity and decoupling of different view controllers.

Roadmap of how to handle asynchronous actions

1. Register for the response of the asynchronous actions. This can be setting the delegate of the requesting object e.g. NSURLConnection to the view controller, which is typically self in this context. The othe possibility is that you register for the notification which is fired by the requesting object if things have happend e.g. when a download is finished or an error occurred.
2. Implement the delegate methods or the notifications to update your model and/or your user interface. Be aware that updating the UI has to happen on your main thread.
3. Start the asynchronous action. What happens in the background is that a separate thread is spawned or an operation is dispatched using GCD. These are implementation details and do not bother you.
4. Wait for the answer, which will result in one of your implemented methods to be executed which you then use to update what has changed.

Difference between notifications and delegates

The two differences between delegates and notifications is that delegate is a one-to-one connection between the delegate and the delegating object. Notifications are posted application wide and can be observed by as many objects as needed creating a one-to-many connection. Think about this as a broadcast. The second main difference is that delegation can be used to transfer information back from the delegate to the delegating object. Meaning that the delegating object asks the delegate for certain information. Typical example would be the data source of an UITableView. Notifications however are a one way street. The information flows from the posting object to the observing objects. This makes sense because think about the situation where you would have more than one observer and each would give feedback to the posting objects. Which one would be the right one?

In your case you would have to look up the delegate methods of the asynchronous HTTP request object and implement them accordingly.

Maybe you can try ASIHTTpRequest , It has Sync an Async request

If you using Async request , you can do anything after you press a button to do a request .

Check this

The solution depends on the response processing.... if you are just showing user that the sms sending is failed/successful than you can do it in any general utility class that shows alert.. but for this you have to create the singletone instance of your connection class so delegate(class itself) don't die when the response comes back.......

For this we need to keep track of currentViewController ....... we can do this by creating a reference ........ id currentViewController in appDelegate(with setter/getters).......... so it could be accessible in everywhere application........

its referred object should be changed each time when user changes the viewController.... that will help us to know on which viewController user is currently working.

than when the singeltone class of connection finished its response loading we can use this currentViewController with your desired viewController.

I am not sure how you are using different view controller....... pushing it/ presenting it or adding its view.....