Geofencing, explained
How it works
A circle around every place on your list. Your phone, not the app, watches whether you cross one.
A circle around every place
When you save a place, GeoStroll draws an invisible circle around the pin you confirmed. You choose how wide: around the corner, nearby, or from afar. A museum gets a wide circle, a bar a small one.
The circle is handed to iOS. From then on your phone, not the app, keeps an eye on it. The app is not running in the background; it is woken up only when you cross the edge.
- 150 m · around the corner
- 300 m · nearby
- 600 m · from afar
Why your battery is fine
Location apps drain batteries when they poll GPS all day. GeoStroll does not poll at all.
The phone does the watching
iOS watches the circles with cell towers and Wi-Fi most of the time and wakes the app only when you enter one. It is the same system that location-based reminders on iPhone use.
No GPS loop, ever
GeoStroll never asks for a continuous position in the background. The only time it tracks you on screen is when you open the map yourself.
The trip ends, the circles go
On your trip's end date every circle is removed. Nothing keeps watching after the holiday.
Twenty circles, moved as you walk
iOS lets an app watch at most twenty circles at a time. Your list can be longer, so GeoStroll watches the nineteen places closest to you and one extra circle: a big one, centred on you.
When you walk out of that big circle, the app wakes up for a moment, picks the nineteen nearest places again, and redraws the big circle around your new position. That is how a list of forty places works with twenty circles.
The app: You left the big circle. Reshuffling the nineteen nearest places.
At the edge of a circle
What happens in the second you walk into a circle, with opening hours on.
- 1
You cross the line
iOS wakes GeoStroll and tells it which circle you entered. Your position itself stays with the phone; the app only learns that you are near that place.
- 2
One question to Google
If you confirmed the place and switched opening hours on, the app sends that place's Google id to Google Maps and asks for today's hours. One request, four seconds at most, nothing stored.
- 3
One of four answers
- OpenA reminder with the hours: "400 m · Open until 20:00". Opening within half an hour: "Opens at 10:00".
- Closing soon"Closes in 45 min — go now or skip". Fifteen minutes or less counts as closed.
- ClosedSilence. No reminder is posted.
- No answerNo connection, too slow, or Google has no hours: "Hours unknown — check first".
- 4
The answer is dropped
The hours are used for that one reminder and then forgotten. GeoStroll keeps nothing from Google except the place's id. A tap on the reminder opens Google's own place card.
The app: Opening hours off? Then no question goes to Google. The reminder says "You're near — tap for hours".
Without a connection
Your places, the circles and the reminders all work offline. Only the hours need a connection, and the app says so up front: an offline reminder reads "Hours unknown — check first".
Permissions, in order
GeoStroll asks for location "While Using the App" first, and for notifications. "Always" is optional and offered later, for reminders with the phone in your pocket. With only the first permission, the app still reminds you whenever it is open or was used recently.