Hi! Can anyone advise how to collect GPS traces using an iPhone? The app “GPS Tracks” available in the iTunes store has great reviews, I just don’t know how to get the data I record on my iPhone, onto my computer so I can upload it to OSM. Any advice is appreciated. TIA 
I use a different app, but maybe the same method works. I use iTunes to transfer the trace files (*.gpx) to my PC as described here. Then I upload the traces to OSM via this page. Maybe your app works the same way.
I use Pocket Earth on my Iphone to record GPS tracks. PE includes a function for easy transfer of gpx-filer to PC or Mac and from there standard upload to OSM.
PE costs 5-6 USD, but worth it.
I use Galileo, easy, clean, and does a great job, developer is still working on it, and pushing updates, you can export GPS Tracks to Cloud Services (Dropbox et al.) or iCloud, Mail, Whatsapp, SMS and so on