Offline OpenStreetMap in the cache

[MikhailDomanov]

Hello Mr Juan M. Merlos, Mr Vincent Neo and all the Team,

This piece of software is just great!

I would like to have OpenStreetMap offline in the app's cache around my location. That is, withing the radius of 200 km. In the summer I travel a lot and change my plans depending on the weather, road conditions and many other factors. As I understand, the app allows to browse areas in advance and to save them into its cache. I cannot see an option to select an area and download all map tiles in all magnifications for a large area with a couple of taps in advance.

I am not a software developer. I cannot quickly read this source code. Thus, I would like to ask if I could download a complete set of map tiles from OpenStreetMap on my PC with Windows, convert it into the cache format used by Open GPX Tracker (1.8.0). I will then put this cache into my (jailbroken) iPhone manually.

I am sure you know a couple of ways I could proceed. Any ideas will be good ideas!

Thank you

[merlos]

Hi Mikhail,

In order to do what you mention you need some basic level of software development or command line scripting.

The process would be to:

1. Download the tiles in your pc saving each tile file should have as name the MD5 hash of the following string urlTemplate-x-y-z where x y z are the number of the tiles, and urlTemplate depends on the map provider. You have the templates used in the app in this linkhttps://github.com/merlos/iOS-Open-GPX-Tracker/blob/4981e2d342e1c4807bb7e44d87f6401cc51be29c/OpenGpxTracker/GPXTileServer.swift#L53

For example the file with the URL:
https://tile.openstreetmap.org/6/32/22.png ---> shall be renamed to the md5 of "https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png-32-22-6". For example in osx you can use md5

md5 -s "https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png-32-22-6" 

Which will give you the output

MD5 ("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png-32-22-6") = 9da6c8c2c6dfed0c3f4369df6cd6a86a

Here 9da...86a is the name you have to assign to the file.

In this other link you have how the url and the key are calculated within the app
https://github.com/merlos/MapCache/blob/13283eaeec68951f330a1229e0bb4ae23e05c789/MapCache/Classes/MapCache.swift#LL53C1-L73C6

2. Once you have the tiles. Copy the files with the md5 name to the temporary folder where the cache is created. It is within the Discache folder within Library/caches in the app folder within your device (see Apple doc

That should be the process. I would check moving some tiles, and using the phone off-line to check if it works. Then, download the full tileset.

Alternatively, in the MapCache repo, the example app allows you to download a region in the map. If you can compile it, it may be an alternative.

Best, Juan.

[MikhailDomanov]

Juan,

This is huge and EXACTLY what I was looking for.
Estoy muy agradecido

Mikhail