I found that sometimes you may be doing something in your iPhone application that requires the user to wait while it completes. Often this is a network related activity, but in other cases it may not be. In my case I was parsing the response from a network connection and wanted the network activity indicator to keep spinning even though it had already downloaded the content.
Here is a quick tip on how to trigger the display of the network activity indicator (spinning icon at the top left of the screen) on an iPhone from within your application:
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// start the indicator ... [UIApplication sharedApplication].networkActivityIndicatorVisible = YES; // Do something that may take some time to complete ... // stop the indicator ... [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;