UIFont extension for (the gradual introduction of) Dynamic Type Sizes, but only enabled in DEBUG mode.

UIFont+DynamicTypeSizes.swift

//
//  UIFont+DynamicTypeSizes.swift
//
//  https://gist.github.com/hoppsen/6b752057b98fa7527ee1f4d4ba05fef0
//
//  More about Apple's Typography can be found here:
//  https://developer.apple.com/design/human-interface-guidelines/ios/visual-design/typography/

import UIKit

extension UIFont {
    /// SFProDisplay, Regular, 34pt
    static let largeTitle: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .largeTitle)
        #else
            return UIFont.systemFont(ofSize: 34.0, weight: .regular)
        #endif
    }()

    /// SFProDisplay, Regular, 28pt
    static let title1: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .title1)
        #else
            return UIFont.systemFont(ofSize: 28.0, weight: .regular)
        #endif
    }()

    /// SFProDisplay, Regular, 22pt
    static let title2: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .title2)
        #else
            return UIFont.systemFont(ofSize: 22.0, weight: .regular)
        #endif
    }()

    /// SFProDisplay, Regular, 20pt
    static let title3: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .title3)
        #else
            return UIFont.systemFont(ofSize: 20.0, weight: .regular)
        #endif
    }()

    /// SFProText, Semibold, 17pt
    static let headline: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .headline)
        #else
            return UIFont.systemFont(ofSize: 17.0, weight: .semibold)
        #endif
    }()

    /// SFProText, Regular, 17pt
    static let body: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .body)
        #else
            return UIFont.systemFont(ofSize: 17.0, weight: .regular)
        #endif
    }()

    /// SFProText, Regular, 16pt
    static let callout: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .callout)
        #else
            return UIFont.systemFont(ofSize: 16.0, weight: .regular)
        #endif
    }()

    /// SFProText, Regular, 15pt
    static let subheadline: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .subheadline)
        #else
            return UIFont.systemFont(ofSize: 15.0, weight: .regular)
        #endif
    }()

    /// SFProText, Regular, 13pt
    static let footnote: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .footnote)
        #else
            return UIFont.systemFont(ofSize: 13.0, weight: .regular)
        #endif
    }()

    /// SFProText, Regular, 12pt
    static let caption1: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .caption1)
        #else
            return UIFont.systemFont(ofSize: 12.0, weight: .regular)
        #endif
    }()

    /// SFProText, Regular, 11pt
    static let caption2: UIFont = {
        #if DEBUG
            return UIFont.preferredFont(forTextStyle: .caption2)
        #else
            return UIFont.systemFont(ofSize: 11.0, weight: .regular)
        #endif
    }()
}