ios - Swift:在启动时显示登录屏幕时防止闪烁

Question

我们的应用程序中有两个 Storyboard。 Storyboard #1 中的默认 View 假定用户之前提供了有效凭据。如果他们没有这样做，我们将“重定向”到 Storyboard #2 中的登录屏幕:

let storyboard = UIStoryboard(name: "Authentication", bundle: nil)
let controller = storyboard.instantiateViewControllerWithIdentifier("LoginController") as UIViewController
presentViewController(controller, animated: true, completion: nil)

这是有效的 - 但是当此代码运行时会出现闪烁，默认 View 会在显示登录 View 之前短暂出现。如何在不闪烁的情况下执行此操作？

Answer 1

您不必将相应的 ViewController 设置为 Appdelegate 本身中的窗口的 rootviewcontroller，而不是呈现 LoginController，如下所示:

self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
//Check for credentials,if value available make LoginStatus as true
if LoginStatus == true{
    //Change Storyboard name "Main" to your "storyboard #1" name.
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    //Change Viecontroller name "My_Offer" to your "DefaultViewController name" name.
    let vc = mainStoryboard.instantiateViewControllerWithIdentifier("My_Offer") as UIViewController
    let navigationController = UINavigationController(rootViewController: vc)
    self.window!.rootViewController = navigationController
}else{
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Authentication", bundle: nil)
    let vc = mainStoryboard.instantiateViewControllerWithIdentifier("LoginController") as UIViewController
    let navigationController = UINavigationController(rootViewController: vc)
    self.window!.rootViewController = navigationController
}
self.window!.makeKeyAndVisible()

这将阻止在呈现 LoginController 之前显示默认 View 。

否则

在 Storyboard #1 中创建一个 DummyViewController(UIViewController) 并将其设为 InitialViewController 并将背景图像(您的启动画面图像)设置为 DummyViewController。在 viewdidload 中检查凭据,如果你有值(value)

let storyboard = UIStoryboard(name: "storyboard #1", bundle: nil)
let controller =     storyboard.instantiateViewControllerWithIdentifier("default view ") as    UIViewController
presentViewController(controller, animated: true, completion: nil)

如果您给定的代码没有凭证

let storyboard = UIStoryboard(name: "Authentication", bundle: nil)
let controller = storyboard.instantiateViewControllerWithIdentifier("LoginController") as   UIViewController
presentViewController(controller, animated: true, completion: nil)

这也可以防止闪烁，但这不是一个好方法。我建议第一种方法设置rootviewcontroller。这可能对你有帮助。试试吧。