iPhone X corner radius?

Hello,

I am currently working on an Xcode project and am rounding the corners of my buttons with a blue background. I became curious as to the proportions of the iPhone X for various reasons and found it was a 375:812 ratio.

I plan to make my button proportional to the size of the iPhone X screen, but cannot find the screen corner radius of the iPhone X anywhere. I figured that it was around 39 pixels by guess and check methods in Xcode doing "button.layer.cornerRadius = 39" when I had my button take up the entire screen compared to 40.

I want to make sure that it is 39, because obviously my method isn't as rock solid as others. If anyone knows the answer please feel free to help!

Thanks