ios - 手动设置 UITabBar selected Item 时遇到问题

Question

我正在 View Controller 中实现自定义 UITabBar。我成功地将 UITabBar 委托(delegate)设置为 UIViewController。

但是，在 viewDidLoad 上，我想使用以下方法选择 UITabBar 的第一项:

tabBar.selectedItem = tabBar.items[0] as UITabBarItem 

但我一直遇到这个错误。

(UITabBar, didSelectItem: UITabBarItem) -> ()' does not have a member named 'selectedItem'

这是我的代码:

class ViewController: UIViewController, UITabBarDelegate {
    @IBOutlet var tabBar : UITabBar!
    @IBOutlet var placeHolderView : UIView!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        tabBar.selectedItem = tabBar.items[0] as UITabBarItem
        switchView(0)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func tabBar(tabBar: UITabBar, didSelectItem item: UITabBarItem) {
        switch item.tag {
        case 0:
            switchView(0)
            break
        case 1:
           switchView(1)
           break
        default:
            break
        }
    }

    ...
}

更新:

让这个工作:

tabBar.selectedItem = tabBar.items![0] as? UITabBarItem

我仍然需要了解可选项...

Answer 1

我发现这个解决方案有效:

override func viewDidLoad() {
    super.viewDidLoad()
    for i in tabBar.items as [UITabBarItem]){
      if i.tag == 0 {
        tabBar.selectedItem = i
        break;
      }
    }
    switchView(0)
 }