I am a Cachly user, a GSAK user, Garmin GPS MAP62s, (now a Map64st) user, and iPhone user.
I believe the gpsr more accurate than the iPhone, especially when I travel into a dead zone.
So I began searching the internet for a way to export from Cachly on my iPhone to my Map64st. Most involved using Basecamp Mobile, which is gone and replaced with Garmin Connect.
Although I couldn't figure out how to export through Connect.
I did figure out away...actually 2 ways.
One involves a lightning to MicroSD card. This involves taking the card out of the gpsr, install in in the lightning reader, exporting the gpx, then upnzipping it on the card, reinserting it and good to go.
The 2nd method lets you keep the card in the gpsr. Using a powered lightning to usb adapter, you can connect the iphone, gpsr, and external usb power, needed to power the iphone and keeping it from becoming overwhelmed by the current draw of the gpsr.
When the gpsr is plugged in, I choose to access the Mass Storage.
In Cachly, I choose the area (in live view) I want to gather caches. In this example, I kept reloading the page until I had 1300.
I exported using the name Caches. It took a while to download.
I then export it into the MicroSD card under a folder named Garmin/GPX
The export is done using a iOS program I downloaded free called iZip, which allows you to placed the caches.zip into many different folders - photos, documents, Google docs, Dropbox, etc, Since it sees the gpsr, I put it under the folder Garmin/GPX, although I could also store it in the internal gps just as easy in the same named folder, which is default on the gpsr.
Once exported, I use iZip to unzip the gpx into the Garmin/GPX folder.
Unplug the usb to gpsr cable, turn on the gpsr, and when it loads it has the 1300 caches loaded from Cachly and my iPhone.
If I travel and leave the 1300 cache area, I can gather caches for the next area and repeat the process. I will use iZip to view the gpx files and delete them and the zip files from off the MicroSd.