It is possible to import waypoints in Topo GPS in the following file formats: gpx, kml/kmz, csv and geojson. Files of these types can also be imported if they are compressed in a zip file.
To import waypoints you could try to tap on a file icon. Most often an app picker will show up. You then have to select ‘Open with Topo GPS’ or ‘Copy to Topo GPS’ and the file will be imported in Topo GPS.
Alternatively you could open the waypoints screen in Topo GPS (Menu > Waypoints) and tap More > Import file. Then the files app will be opened. Here you can select a cloud storage, like iCloud, Dropbox, OneDrive or Google Drive. Then you can browse through your files and select the files you want to import.
If the waypoints were imported succesfully, you will return to the main map screen and the map will be zoomed to the imported waypoints. In the waypoints screen (Menu > Waypoints) all imported waypoints can be found in a newly created folder.
How to import a geodata file from iMessage is explained in a separate section.