AWU2UDDF - Getting Started

Version: 1.1(3)

Updated: December 31, 2022

Introduction

AWU2UDDF is used to export dive profile information that is collected on an Apple Watch Ultra to a Universal Dive Date Format (UDDF) XML file so it can be imported into Subsurface dive log, or any other dive log application that supports the UDDF format. AWU2UDDF uses depth samples stored by the Apple Watch Ultra in the HealthKit data store that is synchronized with a paired iPhone. It queries all of the underwater depth samples in the HealthKit data store and parses the samples into individual dives whenever there is more than a minute between samples. The Apple Watch Ultra stores underwater depth samples to the HealthKit data store every 2-3 seconds whenever it is submerged, even if there is no diving application running.

Prerequisites

• An Apple Watch Ultra with diving data on it (this should work no no matter what diving app you were running, or even without a diving app running.)
• An iPhone that is paired with the Apple Watch Ultra running at least iOS 16.0. This is the phone where you will install the AWU2UDDF application.

Authorizing Access to HealthKit Data

The first time you run AWU2UDDF on your phone (or after new versions are installed) you will need to authorize access to the Underwater Depth information stored in the HealthKit data store. This is the only infomation that AWU2UDDF accesses.

Do do this, press the orange "Authorize HealthKit" button. The HealthKit authorization page should appear. Here you can press the "Turn On All" option, to allow both read and right access to the depth information. The write access is only necessary to be able to detect that the app has been properly authorized -- we don't actually write any depth information into the HealthKit data sore. Then press "Allow" in the upper, right corner.

Exporting a Dive

Once you have authorized access to HealthKit, a list of dives that have been parsed from the Underwater Depth data will appear. You can simply select one of those dives by pressing on it, and the "Export Dive" screen should appear. Press the orange "Export Dive" button and you will be taken into a file browser where you can choose where you want to store the exported file. Once you have chosen a location, you can press "Move" in the upper right corner to save the file.

If you save somewhere in the "iCloud Drive" location rather than the "On My Phone" location, you can then access the UDDF file directly from a Mac that connected to the same iCloud/AppleID account to import the UDDF file into the desktop version of Subsurface.

Caveats

• I am only exporting depth and temperature profile information from HealthKit -- not any diving application specific log information (e.g. Dive site). The application specific info will be a challenge unless the application vendors (e.g. Huish/Oceanic) publish an API.
• The dive is exported in the timezone that the phone is currently set to, not the timezone of the location where the dive was done, so if you're on a dive trip, you may want to export the UDDF files before you get on a plane home or you will need to manually change the dive time when you import them into Subsurface.
• There are no settings or preferences yet, so the app currently displays depths in meters since that is the standard unit that the UDDF format uses. When you import the UDDF file into Subsurface, the units will be changed to match whatever you have in your preferences.
• The user interface is usable, but not "pretty".

Revision History

• Version 1.0(1) - Initial Release with depth data exported
• Version 1.1(1) - Added water temperature data to exported dive profile
• Version 1.1(2) - Fixed issue with dates being truncated in dive list on smaller iPhone screens.
• Version 1.1(3) - Minor UI improvements including sorting dives in descending order by date so the newest dives are at the top of the list.