Licences and Acknowledgements
Tree Years
© 2026 Harald Meyer. All rights reserved.
The app's code, its tree pictures, app icons, start and launch pictures, colours and sounds were made for Tree Years. The parts that come from others are listed below.
Code
Tree Years uses no third-party libraries or Swift packages. It's built only on Apple's frameworks that are part of iOS (SwiftUI, SwiftData, MapKit, Swift Charts, AVFoundation, UIKit, Core Graphics and Foundation).
The suggested tree names are made of word lists written for the app.
Climate data
The climate of Berlin (monthly values for 1991–2020, extremes since 1957) is the basis of the simulated weather.
- Datenbasis: Deutscher Wetterdienst (DWD), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Changed: the monthly values are used to simulate daily weather.
- Days with precipitation and humidity: NOAA National Centers for Environmental Information (NCEI).
- Compiled in the English Wikipedia article "Berlin", section Climate (https://en.wikipedia.org/wiki/Berlin#Climate), retrieved 19 October 2026.
Map
The map on a tree's place screen is provided by Apple Maps through MapKit. Its data sources are listed under "Legal" on the map itself.
Fonts and symbols
The app uses only the fonts built into iOS: San Francisco and, for titles and tree names, New York. No fonts are bundled. Icons in the interface are SF Symbols, provided by Apple as part of iOS.
Pictures
The app icons (in the Field light and Overworld styles), the start screen and launch screen scenes, and the pictures of the starting ages were made for Tree Years from its own tree generator. All trees in the app are painted on the device by the app's own code.
Sounds
The sound of the tree is synthesised on the device from noise, as it plays. The app contains no recordings.
Algorithms
The simulation's random numbers use SplitMix64, written in 2015 by Sebastiano Vigna and dedicated to the public domain (https://prng.di.unimi.it/splitmix64.c). No licence is required; the credit is a courtesy.