This is the app that I use on my mobile to keep track of my Pops. It has some of the best features I've seen. It allows you to imput your collection via barcode scanner and you can view your collections on the web https://www.sortitapps.com
Same program I use on Android just on iPhone. Still $5.99
I use www.poppriceguide.com as another form of collection tracker. You can see a demo of it on the Gallery Page as it shows what I currently have in my collection. Its a free site and has some fun features.