iOS: Programmatically add custom font during runtime

Question

I would like to allow my application users to use their own fonts in the app, by copying them inside the Documents directory (through iTunes). However, I can\'t find a way t

Answer 1

extension UIFont {

    func registerNewFontFromAppBundle(withSize: CGFloat) {
        guard let filePath = Bundle.main.url(forResource: "Art Brewery", withExtension: "ttf") else { return }
        guard let dataProvider = CGDataProvider(url: filePath as CFURL), let cgFont = CGFont(dataProvider) else { return }

        var error: Unmanaged?
        if !CTFontManagerRegisterGraphicsFont(cgFont, &error)
        {
            print("Error registering Font")
        } else {
            guard let uiFont = UIFont(name: cgFont.postScriptName! as String, size: withSize) else { return  }
            CurrentTheme.shared.currentFont = uiFont
        }
    }

    func registerNewFontFromDownloadedFiles(withSize: CGFloat) {
         guard let filePath = FileUtils().getFilePathAtDocumentFolder(fileName: "Art Brewery.ttf") else { return }

        if FileUtils.fileExists(atPath: filePath) {
          let url = URL(fileURLWithPath: filePath)
        guard let dataProvider = CGDataProvider(url: url as CFURL), let cgFont = CGFont(dataProvider) else { return }

        var error: Unmanaged?
        if !CTFontManagerRegisterGraphicsFont(cgFont, &error)
        {
            print("Error registering Font")
        } else {
            guard let uiFont = UIFont(name: cgFont.postScriptName! as String, size: withSize) else { return  }
            CurrentTheme.shared.currentFont = uiFont
            CurrentTheme.shared.currentFontName = cgFont.postScriptName! as String
        }
    }

    }
}

Usage :

UIFont.registerNewFontFromAppBundle(withSize: 30)
UIFont.registerNewFontFromDownloadedFiles(withSize: 30)
mylabel.font =  CurrentTheme.shared.currentFont // saved the font in a Singleton
or 
mylabel.font = UIFont(name: CurrentTheme.shared.currentFontName, size: 30) // Saved the Font name to reuse