My #1 most recommended iPhone photo editing app Snapseed is free right now on the App Store. I use Snapseed 99% percent of the time in my post-processing workflow. The app is consistently updated with new tools and features. If I was lost on a deserted island and could only have my iPhone and one photo editing app, I’d choose Snapseed. Other than retouching or masking, this app does it all. If you don’t already own it, I highly encourage you to get it while it is free. If you miss the sale, get it anyway at full price, you won’t be disappointed.