I have both the official app and Cachly on my iPhone and iPad. For the handful of dollars it cost me Cachly was worth every bit of it and more. The ease of creating TB logs when I have multiple TB's with me alone makes cachly worth it - it's also good for those pesky multi's that require WP projection, can all be done in app & saved as a WP. Filtering on the map is also way better than the official app. I used it with offline maps when I was in Thailand last month and it worked a treat.