This is a simple library I made because I loved what the folks over at Milk have been doing with the indicator on Oink. What it basically does is animate a view to attach to the top of a UIView that you pass in and creates an oscillating effect indicating background processing. This can be a non intrusive way to let your users know that the UI is available, but you're loading some information in the background.
The syntax is really easy to use, but I have a sample app attached just in case.
To show the progressbar:
[TYProgressBar showInView:self.view] // Pass in the correct view here.
You can also tweak it a little by passing in colors that you want instead of a bland white / blue combo like this:
[TYIndeterminateProgressBar showInView:self.view
backgroundColor:[UIColor whiteColor]
indicatorColor:[UIColor greenColor]
borderColor:[UIColor darkGrayColor]];
And to hide the progressBar:
[TYProgressBar hideFromView:self.view]
Here's a screenshot: