Can be easily done using the interface constructor:

View hierarchy
NOTE The background must be a separate view, which is the first entry in the list of controls, so it is in the background. Setting the container view to an alpha value below 1 will also be inherited by subzones that are not displayed in the interface builder

Options for viewing "with clear color bg and alpha 1.0"

Settings for viewing "black translucent viewing bg"

Nick weaver
source share