Mextures is the self proclaimed “best app for applying film grain, textures, light leaks, and beautiful gradients to your images in seconds.” The app’s title “Mextures” is a combination of the words “Mix” and “Textures.” Where Mextures really shines is in its ability to combine layers with non-destructive editing. That means each change you make to a photo can be undone, or tweaked, as you add more effects.
I’ve used Mextures quite a bit, and I love the way you can add gradient, colors, and textures to what would’ve been a very dull photo. Here’s a great example: