Change font in navigation bar in Swift

Question

I'd like to change the font in the navigation bar. However the following code doesn't work, it causes the app to crash.

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

UINavigationBar.appearance().titleTextAttributes = [NSFontAttributeName: UIFont(name: "Lato-Light.ttf", size: 34)!]

     return true
}

I am getting the following error:

fatal error: unexpectedly found nil while unwrapping an Optional value(lldb)

I have indeed added the font Lato-Light.ttf to my project so it should be able to find it.

Answer 1

UIFont() is a failable initalizer, it may fail due to several reasons. A forced unwrap using ! crashes your app.

Better initialize it separately and check for success:

if let font = UIFont(name: "Lato-Light.ttf", size: 34) {
    UINavigationBar.appearance().titleTextAttributes = [NSFontAttributeName: font]
}

And check if your font file is included in the bundle resources.

Common Mistakes With Adding Custom Fonts to Your iOS App

Answer 2

import UIKit

class TestTableViewController: UITableViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        configureView()

    }

    func configureView() {

        // Change the font and size of nav bar text
        if let navBarFont = UIFont(name: "HelveticaNeue-Thin", size: 20.0) {
            let navBarAttributesDictionary: [NSObject: AnyObject]? = [
                NSForegroundColorAttributeName: UIColor.whiteColor(),
                NSFontAttributeName: navBarFont
            ]
            navigationController?.navigationBar.titleTextAttributes = navBarAttributesDictionary
        }
    }

}