I’ve decided to take styles from Xcode and do my best to replicate them for Sketch. Along the way, I documented the process of how I ended up with the result so you can look into things even further.
You'll need to download Apple's SF font: https://developer.apple.com/fonts/
The API doesn't provide any specs for blurs, so it's a challenge to replicate. For performance concerns, I understand why Apple isn't open about these specs. However, as designers I think we shuold be aware of these constraints and design with them.
Apple’s system fonts are designed for legibility and provide a variety of sizes which automatically react to accessibility features. You can read more about why it’s best to use system fonts on the iOS Human Interface Guidelines.
UIFontTextStyle(_rawValue: UICTFontTextStyleTitle1): .SFUIDisplay-Light, 28)