Apple has just approved Open GPX Tracker

Open GPX Tracker is a GPS logger for iOS (iPhone, iPad, iPod). Track your location, add waypoints and send your logs by email as GPX files.

This app has no annoying time restrictions, no ads and no in-app-purchases. Create unlimited GPX traces :)

Requires iOS 7.0 or above. Open GPX tracker is an open source app.

Note: Although, the app supports several tile sources such as OSM, the version published on the App Store, displays Apple Maps.

Here you have some links:

• App Store Download Link
• Source Code
• Open Street Maps Wiki entry of Open GPX Tracker

Enjoy it!