Extensions to help using custom fonts in SwiftUI and UIKit

Font+Extensions.swift

import SwiftUI
import UIKit

/// Custom fonts
enum CustomFont: String {
  case primary = "Topsicle"
  case secondary = "SpaceAndAstronomy"
  case tertiary = "Velezodiac"
}

extension UIFont {
  /// Get the Scaled version of custom UIFont.
  ///
  /// - Parameters:
  ///   - name: Name of the UIFont whose scaled version you wish to obtain.
  ///   - textStyle: The text style for your font, i.e Body, Title etc...
  ///   - size: The font's size. Default value is `nil`
  /// - Returns: The scaled UIFont version with the given textStyle
  static func scaledFont(forFont name: CustomFont, textStyle: UIFont.TextStyle, size: CGFloat? = nil) -> UIFont {
    let userFont = UIFontDescriptor.preferredFontDescriptor(withTextStyle: textStyle)
    let pointSize = size ?? userFont.pointSize
    return UIFontMetrics.default.scaledFont(for: custom(font: name, size: pointSize))
  }

  /// Custom font for UIKit
  /// - Parameters:
  ///   - font: Custom font
  ///   - size: Font size
  /// - Returns: Result font
  static func custom(font: CustomFont, size: CGFloat) -> UIFont {
    guard let customFont = UIFont(name: font.rawValue, size: size) else {
      fatalError(
        """
        \n❌ Failed to load the "\(font.rawValue)" font.
        Make sure the font file is included in the project and the font name is spelled correctly.\n
        """
      )
    }
    return customFont
  }
}

extension Font {
  /// Custom font for SwiftUI
  /// - Parameters:
  ///   - font: Custom font
  ///   - size: Font size
  /// - Returns: Result font
  static func custom(font: CustomFont, size: CGFloat) -> Font {
    Font.custom(font.rawValue, size: size)
  }
}

Font+ExtensionsExample.swift

import SwiftUI

struct InfoView: View {
  var body: some View {
    VStack(alignment: .leading, spacing: 24) {
      VStack(alignment: .leading, spacing: 8) {
        Text("Aries")
          .fontWeight(.semibold)
          .textCase(.uppercase)
          .font(.custom(font: .secondary, size: 17))
          .lineLimit(1)
          .frame(maxWidth: .infinity, alignment: .leading)

        Text("Cautious")
          .frame(maxWidth: .infinity, alignment: .leading)
          .font(.custom(font: .primary, size: 14))
          .opacity(0.7)
      }

      Text("MAR 21 - APR 20")
        .textCase(.uppercase)
        .font(.custom(font: .primary, size: 12))
        .foregroundColor(.quickSand)
    }
    .padding(4)
  }
}

struct InfoViewPreviews: PreviewProvider {
  static var previews: some View {
    SignInfoView()
      .preferredColorScheme(.dark)
      .previewLayout(.sizeThatFits)
  }
}