Swift - How to change UITabBarItem badge font?

Question

I have a UITabBar. I set a value for tab bar items:

tabBarItem3?.badgeValue = String(self.numberOfProducts)

Now I want to change its font to a specific font. Then I used this code :

tabBarItem3?.setBadgeTextAttributes([NSFontAttributeName: UIFont(name: "IRANSans", size: 14)], for: .normal)

It doesn't work. What should I do?

Answer 1

Swift 3

UITabBarItem.appearance().setBadgeTextAttributes([NSFontAttributeName: UIFont(name: "IRANSans", size: 14)], for: .normal)
UITabBarItem.appearance().setBadgeTextAttributes([NSFontAttributeName: UIFont(name: "IRANSans", size: 14)], for: .selected)

Answer 2

UIKit updates the badge font sometime after the view's layoutSubviews or viewWillAppear. Fully overriding this will need a bit of code. You want to start by observing the badge's font change.

tabBarItem.addObserver(self, forKeyPath: "view.badge.label.font", options: .new, context: nil)

Now once the observe method is called it's safe to set the badge font. There's one catch however. UIKit wont apply the same change twice. To get around this issue first set the badge attributes to nil and then reapply your font.

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "view.badge.label.font" {
        let badgeAttributes = [NSFontAttributeName: UIFont(name: "IRANSans", size: 14)]
        tabBarItem?.setBadgeTextAttributes(nil, for: .normal)
        tabBarItem?.setBadgeTextAttributes(badgeAttributes, for: .normal)

    } else {
        super.observeValue(forKeyPath: keyPath, of: object, change: change, context: context)
    }
}

Just incase of future iOS updates, you might want to wrap the addObserver in a try-catch. Also don't forget to remove the observer when your done!

Answer 3

Try this two functions from UITabBarController extension:

var tabBarController : UITabBarController

bottomBar = UITabBarController()

... 
... 
... 

 // Change badge font size
bottomBar.setBadgeFontSize(fontSize: 10.0)


 // Change badge font
bottomBar.setBadgeFont(font: UIFont.boldSystemFont(ofSize: 12.0)) 

Swift 4

extension UITabBarController {

  /**

   Change the badge font size of an UITabBarController item.

   - Parameter fontSize: new font size
   - Parameter subviews: nil or optional when called from UITabBarController object.

   Example of usage (programmatically):

   ```
   let bottomBar = UITabBarController()
   ...
   ...
   ...
   bottomBar.setBadgeFontSize(fontSize: 10.0)
   ```
   */
  func setBadgeFontSize(fontSize: CGFloat, subviews: [UIView]? = nil) {

    let arraySubviews = (subviews == nil) ? self.view.subviews : subviews!

    for subview in arraySubviews {
      let describingType = String(describing: type(of: subview))
      if describingType == "_UIBadgeView" {
        for badgeSubviews in subview.subviews {
          let badgeSubviewType = String(describing: type(of: badgeSubviews))
          if badgeSubviewType == "UILabel" {
            let badgeLabel = badgeSubviews as! UILabel
            badgeLabel.fontSize = fontSize
            break
          }
        }
      } else {
        setBadgeFontSize(fontSize: fontSize, subviews: subview.subviews)
      }
    }

  }

  /**

   Change the badge font size of an UITabBarController item.

   - Parameter font: new font
   - Parameter subviews: nil or optional when called from UITabBarController object.

   Example of usage (programmatically):

   ```
   let bottomBar = UITabBarController()
   ...
   ...
   ...
   bottomBar.setBadgeFont(font: UIFont.boldSystemFont(ofSize: 12.0))
   ```
   */
  func setBadgeFont(font: UIFont, subviews: [UIView]? = nil) {

    let arraySubviews = (subviews == nil) ? self.view.subviews : subviews!

    for subview in arraySubviews {
      let describingType = String(describing: type(of: subview))
      if describingType == "_UIBadgeView" {
        for badgeSubviews in subview.subviews {
          let badgeSubviewType = String(describing: type(of: badgeSubviews))
          if badgeSubviewType == "UILabel" {
            let badgeLabel = badgeSubviews as! UILabel
            badgeLabel.font = font
            break
          }
        }
      } else {
        setBadgeFont(font: font, subviews: subview.subviews)
      }
    }
  }

}

Answer 4

Swift 3

UITabBarItem.appearance().setTitleTextAttributes([NSFontAttributeName: UIFont.systemFont(ofSize: 10)], for: .normal)
UITabBarItem.appearance().setTitleTextAttributes([NSFontAttributeName: UIFont.systemFont(ofSize: 10)], for: .selected)