iphone - 为什么 “Use of undeclared type leftViewController” 发生在 Swift 中？

Question

当我在 Swift 中运行时，为什么会出现错误 Use of undeclared type leftViewController？

var centerContainer: MMDrawerController?
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    _ = self.window!.rootViewController

    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)

    let centerViewController = mainStoryboard.instantiateViewControllerWithIdentifier("ViewController") as! ViewController

    let leftViewController = self.mainStoryboard?.instantiateViewControllerWithIdentifier("leftViewController") as! leftViewController

    let rightViewController = mainStoryboard.instantiateViewControllerWithIdentifier("rightViewController") as! rightViewController

    let leftSideNav = UINavigationController(rootViewController: leftViewController)
    let centerNav = UINavigationController(rootViewController: centerViewController)
    let rightNav = UINavigationController(rootViewController: rightViewController)

    centerContainer = MMDrawerController(centerViewController: centerNav, leftDrawerViewController: leftSideNav,rightDrawerViewController:rightNav)

    centerContainer!.openDrawerGestureModeMask = MMOpenDrawerGestureMode.PanningCenterView;
    centerContainer!.closeDrawerGestureModeMask = MMCloseDrawerGestureMode.PanningCenterView;

    window!.rootViewController = centerContainer
    window!.makeKeyAndVisible()


    return true
}

Answer 1

您必须将 leftViewController 和 rightViewController 转换为 UIViewController(而不是 View Controller 实例的名称):

let leftViewController = self.mainStoryboard?.instantiateViewControllerWithIdentifier("leftViewController") as! UIViewController
let rightViewController = mainStoryboard.instantiateViewControllerWithIdentifier("rightViewController") as! UIViewController