Which to use when? NSURLConnection vs. lower level socket API

I am developing an iPhone application which streams data(e.x.ECGData like points) from a server and displays(means Plotting) it on the screen -- i.e., live streaming. For that purpose, I am using NSURLConnection.

The problem I am facing is that, s开发者_开发问答ince the data is coming so speedily from the server to the iPhone, the cache buffer is increasing rapidly, causing the displayed data to lag behind the actual data coming from the server. After some time, the application goes too slowly, and gets a memory warning.

So my question is, how should I handle this data coming from the server? Should I continue with NSURLConnection or go for lower level socket programming?

I propose you implement some sort of flow control:

The simplest approach is to drop data if your buffers are full. For video streams, frames can be dropped. I don't know whether the same is possible with your data.

Another approach is to switch from the event-based API of NSURLConnection (where the framework controls when you have to react) to CFSocket class where you can read data when you are ready for it. It's more low-level, requires a separate thread and some advanced logic like going to sleep when the buffer is full and being woken up when the main thread has displayed more data and made more space in the buffer. With this approach you are basically building on top of TCPs flow control mechanism.

Yet another approach would be to use another network protocol where you have more control about the amount of data being sent.

I would use ASIHttpRequest streaming. You can implement a delegate method request:didReceiveData: to get your data in chunks as it comes in, deflate it if needed pares it and display. If you need cache you can always save it to file.