从一个视图控制器切换到另一个视图控制器，无需用户交互

Question

我试图弄清楚如何编写代码，使一个视图控制器转到另一个视图控制器，而无需按下按钮即可转到第二个。

几乎相同的东西 LaunchScreen.storyboard 无需按下按钮即可转到 Main.storyboard，它只是自动执行。我是编码新手，非常感谢任何帮助。

Answer 1

是的，您可以在不执行任何操作的情况下推送或呈现另一个视图控制器。你只需要在你想触发它的地方调用 push 或 present 代码。

例如： 如果您希望它在计时器功能上触发，请在此处添加您的推送或呈现代码。

//I added this code in first viewController's viewDidAppear, so your second controller will be called after 10 seconds.
    override func viewDidAppear(_ animated: Bool) {

    super.viewDidAppear(animated)

    //If you are using Storyboard
    //10.0 seconds
    DispatchQueue.main.asyncAfter(deadline: .now() + 10.0) {

        //If your first viewController is in Navigation stack
        if let secondViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "SecondViewControllerID") as? SecondViewController {

            if let navigator = self.navigationController {

                navigator.pushViewController(secondViewController, animated: true)
            }
        }

        //If your first viewController is NOT in Navigation stack
        if let secondViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "SecondViewControllerID") as? SecondViewController {

            self.present(secondViewController, animated: true, completion: nil)
        }
    }
 }

参考这个帖子：How to push and present to UIViewController programmatically without segue in iOS Swift 3

Answer 2

这取决于您实际希望如何显示视图控制器。

如果您尝试复制启动屏幕，那么您可能不希望将下一个 VC 推入堆栈。

我想您提供的信息的最佳选择是在短暂延迟后更改 rootViewController。应该这样做：

let delayInSeconds = 5.0

DispatchQueue.main.asyncAfter(deadline: .now() + delayInSeconds) { in

    let appDelegate = UIApplication.shared.delegate as? AppDelegate
    let vc = ViewController()
    appDelegate?.window?.rootViewController = vc
}