GPX is a standard file format to exchange routes, tracks and waypoints. Trails supports this format for importing and exporting data.

You can import GPX files from anywhere in iOS, e.g. from email attachments, the Files app, or Safari. This usually happens via the "Open in…" menu. For example, tap a GPX file in an email attachment, select Open in… and then tap Trails. Trails will be launched and will import the GPX file automatically.

Alternatively you can start the import from within Trails. From the main screen, tap Import in the upper right corner. This screen allows you to directly import tracks from gpsies.com (optionally, filtered by activity type), web URLs (please ensure that the URL points to a GPX file and is accessible without login) or the Files app.