I've never been completely satisfied with the solutions available to keep your iPhone and other touchscreens clean. Let's face it, they get dirty almost as fast as you can clean them with a traditional spray bottle of cleaner and a microfiber cloth.
The HANS Swipe-Clean system is simple a two-sided applicator that just happens to be the exact width of my iPhone 5. Pop the cap off on the Cleaning Side and wipe the screen once or twice. Flip the applicator over and use the Polishing Side to finish. A single unit is said to last approximately 500 swipes and there is a refill bottle available that lasts for about 6,000 swipes. You can clean excess grime on the Cleaning Side by pressing it straight down and swiping onto a clean sheet of white paper. You can clean the Polishing Side with warm water and mild soap once it gets soiled.
I tried the HANS Swipe-Clean on my iPad Mini as well, and it really does a fine job producing a streak-free screen, and according the HANS, removing germs as well. Available at: hans-swipe.com and Amazon. The Swipe-Clean is $18 and a refill is $7. Two Swipe-Cleans and a refill are $38.