ios - 如何在 Swift 中选定的 UITabBarItem 图标下方添加小图标

Question

我有一个 UITabBarController 子类，我想在选定的 UITabBarItem 图标下方添加一个白色的小矩形图标。我使用了 UIView 并将 TabBarItem 作为 subview 并将 View 作为 subview 添加到它。我在 viewWillAppear 中执行此操作，它会显示，但是当我选择另一个选项卡时，它不会出现在该选项卡栏项目下。这是我的代码:

let view =  orderedTabBarItemViews()[selectedIndex]

bottomIcon.frame = CGRect(x: 0, y: 42, width: 10, height: 3)
bottomIcon.center = CGPoint(x: view.bounds.size.width / 2, y: view.bounds.size.height / 2)
bottomIcon.backgroundColor = UIColor.white
bottomIcon.layer.cornerRadius = 2

view.addSubview(bottomIcon)

orderedTabBarItemViews() 函数获取 TabBarItem 作为 UIView 的数组。这是我要实现的目标的图像

Answer 1

这是我使用 unicode 字符创建的快速 hack ⬬:

extension UITabBarController {

    func addDotToTabBarItemWith(index: Int,size: CGFloat,color: UIColor, verticalOffset: CGFloat = 1.0) {

        // set distance from tab bar icons
         for tabItem in self.viewControllers! {
            tabItem.tabBarItem.titlePositionAdjustment = UIOffset(horizontal: 0.0, vertical: verticalOffset)
        }

        // set default appearance for tabbar icon title
        UITabBarItem.appearance().setTitleTextAttributes([NSForegroundColorAttributeName: color,NSFontAttributeName:UIFont(name: "American Typewriter", size: size)!], for: .normal)
        UITabBarItem.appearance().setTitleTextAttributes([NSForegroundColorAttributeName: color,NSFontAttributeName:UIFont(name: "American Typewriter", size: size)!], for: .selected)

        // place the dot
        guard let vc = self.viewControllers?[index] else {
            log.error("Couldn't find a TabBar Controller with index:\(index)")
            return
        }

        vc.tabBarItem.title = "⬬"
    }
}