One of the things that really reflected Apple's mission to “do thing simple and elegant” was the release of iOS 7 a couple years ago (2013). Suddenly you didn't have to use color fill in the background when you wanted things to stand out. ☝🏼
A subtle blur can make your UX look intuitive and slick at the same time. Though the iOS design was slightly improved since then, the blur remained pretty much the same... Maybe it's because it's super easy to imitate it. 🤓 Look:
Blur it step by step:
Bam! You're all set! 🏁
Let us know if know any cool tricks in Sketch in the comments below.