In Codifi a crew had to say what a thing was before they could record it. That kept the data clean. It also slowed down the moment someone just needed to grab something and move on.

So Tephra adds a faster path. A photo, a note, a voice note or a shape goes in with one tap and shows only what matters in that moment. The app helps sort it into a full feature later and offers one from the captures nearby. When you already know what a thing is you can still record it in full straight away.

Working with crews in the sun taught me what a phone is like outside. The screen washes out. Gloves miss small buttons. A soil color picked from a list of Munsell codes is easy to get wrong.

So the buttons are bigger and the form shows a shovel test at a glance. Soil color is picked from chips you can see, each with its notation and name.

Archaeologists sort what they find. Diagnostic artifacts go back with them. Non-diagnostic ones are only documented and left where they lie. The record made in the field is all there will ever be.

A 3D scan of each one keeps far more than a photo. It also gave me a way into augmented reality. I learned Apple’s Object Capture by scanning a brick outside with no signal. I learned ARKit by setting the model back down on a counter.

In the field the phone is the device most likely to die. It collects all day while it runs the GPS. Crews end up carrying spare batteries. Some notes are quicker said than typed anyway and some hands are full.

So on the Apple Watch a voice note is one tap. It stays on the watch until the phone is ready to take it, then plays on the phone and is turned into words there. Every note taken on the wrist is load the phone doesn’t carry.

Survey crews have to account for the ground they cover. A track of the day was one of the things they asked Codifi for most and React Native couldn’t keep it running.

Native code can. The day log is a light GPS track of the whole day kept in a pocket and saved as GPX, with a Live Activity on the Lock Screen and a Stop that works without opening the app.

• A walker’s settings. iOS rests the GPS while the phone stands still and wakes it when it moves. People stop all the time on a site.
• Fewer points. One every 10 meters. Nothing worse than 40 meters is kept.
• Written as it goes. A phone that dies keeps everything up to that moment.

Battery is the problem every crew runs into. A phone that collects all day and runs the GPS is the first thing to die. So the Apple Watch can take the day over. At 15% the phone offers it the day. The phone can’t start the watch itself. Its notification shows on the wrist though. One tap there carries the day on. If the phone dies the watch keeps recording and hands the file over once it’s charged.

A crew member can switch between the phone and the watch through the day and the track stays whole. Some people would rather keep the GPS on the watch from the start. They can.

Handing the day between devices makes one mistake easy. Someone forgets to stop and drives off with the log still running.

So each day has a screen of its own, with a calendar and each track’s map and elevation and a time to drag along it. The drive can be cut out of the track without deleting the day or losing the rest of the GPX.

On my first field test the GPS dropped out during a six-minute phone call and the track drew 4.2 km (2.6 miles) of road as one straight line. Now the file marks where the GPS was lost and starts a new line when it’s back. A day on the watch alone used 10% of its battery in 1 hour 37 minutes.

Crews work from the map all day. Nothing should take it away. Find My does this well. It keeps a sheet over its map that never goes away and the map behind it keeps working.

People keep asking on Apple’s forums how to build it. SwiftUI’s sheet covers the tab bar. So the dock is a UIKit tab bar controller presented as the sheet itself, with SwiftUI pages inside.

The hard part was the bar. UIKit melts a tab bar into a sheet’s glass only near a detent with one private name. So the dock’s resting height is a public detent that carries the same name. I found it by tracing UIKit itself.

Survey work needs better than a phone’s few meters. Agencies set how close a point has to be and a phone’s own GPS often can’t get there.

So I built the iPhone side of a Bluetooth receiver, which was the time with connected accessories I was after: the system’s own pairing picker, then NMEA sentences read as they stream in, each checked before anything trusts it. I tested it with a SparkFun RTK Facet.

In the recording the phone’s own fix is good to 7 meters. The Facet’s is good to 0.81 meters before any corrections.