I was always checking for my phone in my pocket the past two years so this year I decided to finagle a retractable key reel to my iPhone. It worked perfectly and I never felt that paranoia of someone snatcing my phone from my pocket.
Here is the Key Reel: https://www.amazon.com/gp/product/B0039YY2QM/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
Here is the case holder that would attach to the Key Reel: https://www.amazon.com/gp/product/B075S18ZFZ/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1