Oilcalcs for iPhone iOS 13 version 1.4.1 has been approved by Apple and is now available for download here.
The new version of OilCalcs has been improved for viewing in dark mode, for iPhones that have iOS 13.0 or higher installed.
Various minor bugs have also been fixed. See below for a view of the various screens in dark mode:
Oilcalcs for iPhone can be downloaded from the App Store here: