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UIProgressHUD when shown, and set to "done" state respectively.

UIProgressHUD is a view which occupies the whole window for showing a short progress message. This view is private, that means you shouldn't use them for AppStore apps, but alternatives[1] exist.

Also note that UIProgressHUD is just a normal view. It will not block interactions to other background views.

Using UIProgressHUD

UIProgressHUD* hud = [[UIProgressHUD alloc] initWithFrame:CGRectZero];
[hud setText:@"Loading, please wait."];
[hud showInView:someView];
[hud done];
[hud hide];
[hud release];