Swift - 如何更改UITabBarItem徽章字体？

Question

我有一个UITabBar。我为标签栏项设置了一个值：

tabBarItem3?.badgeValue = String(self.numberOfProducts)

现在我想将其字体更改为特定字体。然后我使用了这段代码：

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

它不起作用。我该怎么办？

Answer 1

斯威夫特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在视图的layoutSubviews或viewWillAppear之后的某个时间更新徽章字体。完全重写这将需要一些代码。您希望从观察徽章的字体更改开始。

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

现在，一旦调用了observe方法，就可以安全地设置徽章字体。但是有一个问题。 UIKit不会两次应用相同的更改。要解决此问题，首先将徽章属性设置为nil，然后重新应用您的字体。

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)
    }
}

在未来iOS更新的情况下，您可能希望将addObserver包装在try-catch中。完成后别忘了删除观察者！

Answer 3

尝试UITabBarController extension的这两个函数：

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)) 

斯威夫特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

斯威夫特3

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