Just use lint free cloth to clean the iPhone screen. Some alcohol solvents can damage the oleophobic coating. Just wash your hands with soap and water, the dry them completely before touching iPhone.

How to clean Apple products

Clean iPhone immediately if it comes into contact with any contaminants that may cause stains, such as ink, dyes, makeup, dirt, food, oils, and lotions. To clean iPhone, unplug all cables and turn off iPhone (press and hold the Sleep/Wake button, and then slide the onscreen slider). Use a soft, slightly damp, lint-free cloth. Avoid getting moisture in openings. Don’t use window cleaners, household cleaners, aerosol sprays, solvents, alcohol, ammonia, or abrasives to clean iPhone. The front and back glass surfaces have an oleophobic coating. To remove fingerprints, simply wipe these surfaces with a soft, lint-free cloth. The ability of this coating to repel oil will diminish over time with normal usage, and rubbing the screen with an abrasive material will further diminish its effect and may scratch the glass.