I am displaying a modal view with
[self presentModalViewController:controller animated:YES];
When the view moves up the screen it is transparent as per the setting in the xib file it is created from, but once it fills the screen it goes opaque.
Is there anyway of keeping the view transparent?
I suspect that the view it is being placed over is not being rendered rather then that the modal view is becoming opaque.
Your view is still transparent, but once your modal controller is at the top of the stack, the view behind it is hidden (as is the case with any top-most view controller). The solution is to manually animate a view yourself; then the behind-viewController won't be hidden (since you won't have 'left' it).