Sometimes it's desirable to display an important confirmation message (e.g. you've successfully registered/sent this form/etc) that doesn't get in the way by requiring a "dimiss" button. Is there a standard way of doing this?
Apple apps have a translucent progress display, but it’s an undocumented API. Here is an open source version I came across recently. I haven't tried it yet, but it may meet your needs. The picture shown below is an example given on the github site.
There is no standard way to do it as you think.
Be careful when it comes to using Progress HUD in iOS apps. Progress hud is normally used in situations, where the device is working on a process that takes too long and the user should not be able to manipulate with the screen. For example, when the device is processing an image. This is the right place to use progress HUD.
Also apple uses HUDs for example to notify the user that sound levels have changed.. So please, do not mix these with notifying user that the user was successfully registered/sent this form/etc.
Right pattern to notify the user about these stuff comes out directly from context of your app design. For example, when the user fills up a registration form, and taps to register, try to show a progress on the title view of the navigation bar while the process of registration ends and after that, simply dismiss your modal view controller (lets hope you use modal in this situation). These animations are the right method to present feedback to the user. If there is an error, you can simply present alert, although there are also better ways to present an error.
I believe that showing progress hud is as much disturbing to the user as showing an alert view, even thought he doesn't have to dismiss it.
note: please please please, do not use progress hud to show network progress ;)