Message users while large table loads

I am processing several large RSS feeds and displaying results in a TableView. The processing starts after the user clicks on the relevant tab. All works well, but as it takes a couple of seconds to process, the NIB and Table don't load until the processing finishes and it looks like the iPhone has seized up. I have added an Activity indicator to the NIB, but because it doesn't load until the table is ready to display, it appears too late to be of any use.

Does anyone have any ideas how to display a message to a user while the table builds/loads? I have tried loading a UIView first 开发者_如何学运维and adding the Table as a subview but, again, both seem to load only after the table is ready.

Guidance appreciated.

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It's kind of hard to guess what's going on from your description but it looks like your calls aren't asynchronous. Here's what you should be doing in your code:

1. Make all calls asynchronous. You said your phone is seizing up. Makes it sound like your requests and responses are happening on the main thread. There are many libraries you could use to handle asynchronous calls. ASIHTTPRequest for one example....

2. Don't wait for the data to come in before displaying the tableView. It's a design principle that you load as much of the UI as possible so that the user has something to look at while your data loads up in the background. What you should be doing is initializing an NSMutableArray to hold the data. Initially this array will contain no objects. This is the array that you use in your data source methods: Use array size for numberOfRowsInSection and use the array objects in cellForRowAtIndexPath. Once your RSS feed XML comes in and is parsed, store that in your arrays and call [tableView reloadData]. This way you don't leave your users looking at a blank screen. (Another good practice is when the array size is zero, show one cell in your tableview that says "data is loading" or something).

3. When you first initialize and load up your table and then fire off those RSS feed requests, that's where you show an activity indicator view on the tableView. Stop animating the indicator when the RSS data comes in and your tableView reloads.

These are the standard steps you should follow while showing non local data in a tableview. Makes for a smooth user experience.

Like I said before, it seems from your question that your calls are not asynchronous. If I'm wrong, correct me and let's take it from there...