Here is a small tutorial on creating offline maps for iphone using GMDL. You can find more detail in my other post.
1. First of all you need to have a jailbroken iPhone or iPod and you should know how to transfer files into your iphone/ipod.
2. Download the “OfflineMaps”, App from Cydia by using the Search Menu.
3. If you wish to make maps for your own area, download Global Map Download Tool (from www.in7ane.com) extract it and then open “/GMDL/bin/debug/Global Map Download Tool.exe”
4. It will open Google Maps website inside the tool. Search for the area for which you want the map.
5. when it appears, click the “preview 1x” button at top left.
6. It will show the area for which maps will be downloaded.
8. It will ask for a directory to save the map files. Create a new one.
9. it will show the selected map in form of small tiles. Uncheck the unwanted tiles and the zoom level 1 & 2. It will keep the size of map to a reasonable limit. when done press the button at the top for download to start
10. Status bar will show the download progress. Wait till the download is complete and a message for the same appears.
11. Now click the “iphone” button at the top left to convert the maps to a format understandable by Iphone.
12. A pop-up window will appear. Select the firmware version of Iphone.
13. Click the “process” button to start conversion. By default it saves the files in desktop\iphone_map folder. If this folder already exists then change the name of output directory in pop-up window. It creates directory itself so you don’t need to create one.
14. After successful completion it a pop-up message appears. Now you have the files in desktop\iphone_map folder available for transfer.
15. Now, transfer your files to the device using software like DiscAid (or Iphone Browser). Download and install DiscAid , and then on the left hand side under “Media” folder, there is a “Maps”, folder. If there isnt one there click on the Media Folder which is the very first one on the left side and then click “Create Folder”, and then name it “Maps”.
16. In this maps folder make a folder which is <4 letters long that corresponds to the map you have made. It just has to be less than 4 characters. In that folder copy “com.apple.Maps.plist”, and “MapTiles.sqlitedb”.
17. Now open the “OfflineMaps”, app on your device and see if the maps show up on the list. If they do everything has worked great, otherwise trackback and see if you have made a mistake.
If your maps are there, select it and then press the “Link”, button and wait till it says “OK”, press the home key and the OfflineMaps icon should have the letters of the map u selected on it.
Now fire up maps and you should be able to browse freely. remember to turn off network access when you are browsing outside of the cached area.