NSFontAttributeName has changed to String

问题:

i'm trying to style the navigation bar properly, i need to change the font to helvetica neue with a size point of 19. I've ever used this code but i've notice that now doesn't work as well:

navigationController?.navigationBar.titleTextAttributes = [NSFontAttributeName: UIFont(name: "HelveticaNeue-Light", size: 19)]

this happens because the type of NSFontAttributeName has changed to String, i've tried to fix it with

navigationController?.navigationBar.titleTextAttributes = [NSFontAttributeName: "HelveticaNeue-Light, 19"]

but the compiler continue to give me an error related to point size in font, how can i fix it?

回答1:

The UIFont constructor is returning an optional (UIFont?) which you must unwrap to use. Add ! if you're sure you have a valid font name:

Swift 4.2:

navigationController?.navigationBar.titleTextAttributes = [NSAttributedString.Key.font: UIFont(name: "HelveticaNeue-Light", size: 19)!]

Swift 4:

navigationController?.navigationBar.titleTextAttributes = [NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 19)!]

Swift 3:

navigationController?.navigationBar.titleTextAttributes = [NSFontAttributeName: UIFont(name: "HelveticaNeue-Light", size: 19)!]

Note: If you are setting a font with a static name in your code, then force unwrapping is safe once you’ve verified you’re using a valid font name. If you are getting the font name from an external source (the user or a server), you will want to use optional binding such as if let font = UIFont(... or guard let font = UIFont(... to safely unwrap the font before use.

回答2:

With Swift 4 NSFontAttributeName is deprecated, you can use NSAttributedStringKey values to set attributes.

if let fontStyle = UIFont(name: "HelveticaNeue-Light", size: 19) {
  navigationController?.navigationBar.titleTextAttributes = [NSAttributedStringKey.font: fontStyle]
}

With Swift 4.2 NSAttributedStringKey is changed as NSAttributedString.Key.

if let fontStyle = UIFont(name: "HelveticaNeue-Light", size: 19) {
  navigationController?.navigationBar.titleTextAttributes = [NSAttributedString.Key.font: fontStyle]
}

For more options for NSAttributedStringKey you can visit this link https://developer.apple.com/documentation/foundation/nsattributedstringkey/

回答3:

Swift 4.2

NSAttributedStringKey has renamed to NSAttributedString.Key in Swift 4.2

if let fontStyle = UIFont(name: "HelveticaNeue-Light", size: 19) {
  navigationController?.navigationBar.titleTextAttributes = [NSAttributedString.Key.font: fontStyle]
}