I'm an Android user. (Google Pixel 2XL)
I did end up getting the Tractor Guidance App and the Garmin Glo. The jury is still out on it's effectiveness... It tracks pretty well but does not seem to get my location accurately enough to really rely on. It's seems to be good for setting up your pattern and drawing parallel lines at the input spray swath, but sometimes it seems like the location accuracy is lacking.
Free Farmis "Field Navigator" app for android with a $99 Garmin Glo2 satellite antenna is what I use to spray my fields. Maybe I'll add foam markers at some point, this system works great, but accuracy can vary sometimes, according to satellite availability. What does everyone else use?
You get what you pay for. It's $100 for the Garmin glo and a free app, that gives you a good idea of where you are in the field, but isn't accurate enough to plant row crops with like John Deere's expensive units. I use it to spray and it keeps me more or less on track, and it's especially handy in showing where the major skips are after I'm finished.
I would say that sounds similar to my experience with the Iphone app and the Garmin glo. It keeps me on track and helps identify major gaps. The user interface on the Iphone Tractor Guidance app looks very similar to the pics Mennoniteman posted at the start of the thread.
