Question

我有一个获取推送通知的应用程序，它通常显示一个模式。

当用户出于某种原因显示UIAlertController时就会出现问题。我得到了著名的

Warning: Attempt to present <ViewController> on <ViewController> which is already presenting <UIAlertController>

我在一个带有单个UIViewController的基本应用中使用以下代码创建了这种情况：

class ViewController: UIViewController {
    var color: UIColor = .red

    let alertController = UIAlertController(
        title: "Title",
        message: nil,
        preferredStyle: .alert
    )

    override func viewDidLoad() {

        super.viewDidLoad()

        view.backgroundColor = color

        let alertButton = UIButton()
        alertButton.translatesAutoresizingMaskIntoConstraints = false
        alertButton.setTitle("alert", for: .normal)
        let alertGesture = UITapGestureRecognizer(
            target: self,
            action: #selector(alert)
        )
        alertButton.addGestureRecognizer(alertGesture)

        let dismissButton = UIButton()
        dismissButton.translatesAutoresizingMaskIntoConstraints = false
        dismissButton.setTitle("Dismiss", for: .normal)
        let dismissGesture = UITapGestureRecognizer(
            target: self,
            action: #selector(dismissVC)
        )
        dismissButton.addGestureRecognizer(dismissGesture)

        let modalButton = UIButton()
        modalButton.translatesAutoresizingMaskIntoConstraints = false
        modalButton.setTitle("modal", for: .normal)
        let tapGesture = UITapGestureRecognizer(
            target: self,
            action: #selector(modal)
        )
        modalButton.addGestureRecognizer(tapGesture)

        view.addSubview(alertButton)
        view.addSubview(dismissButton)
        view.addSubview(modalButton)

        NSLayoutConstraint.activate([
            alertButton.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            alertButton.topAnchor.constraint(equalTo: view.topAnchor, constant: 50),

            dismissButton.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            dismissButton.topAnchor.constraint(equalTo: view.topAnchor, constant: 50),

            modalButton.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            modalButton.topAnchor.constraint(equalTo: view.topAnchor, constant: 50),
        ])

        alertController.addAction(UIAlertAction(title: "Yes", style: .cancel, handler: nil))

        alertController.addAction(UIAlertAction(title: "No", style: .default, handler: { _ in self.alertController.dismiss(animated: false, completion: nil) }))

    }


    @objc func dismissVC() {

        self.dismiss(animated: false, completion: nil)
    }

    @objc func alert() {

        self.present(alertController, animated: true, completion: nil)

        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {

            self.modal()
        }
    }

    @objc func modal() {
        print("modal")

        let newVC = ViewController()
        newVC.color = .clear
        present(newVC, animated: true, completion: nil)
     }
    }

因此，我在这里意识到了这个问题，我试图在同一个视图控制器中呈现两个视图控制器。

我将如何解决这个问题？我也尝试通过UIAlertController展示模式，但是我很高兴没有奏效（警报被重新定位到了意外的位置），因为那将是一个主要的黑客。

我还尝试过解除UIAlertController的作用，展示模态，并从该新模态中展示UIAlertController，但是看起来也不是很好...

我唯一剩下的想法是创建一个队列并仅在解除警报时显示模式。我认为该实现在这里是不必要的。

感谢您的想法

iOS-在显示UIAlertController时（以模式方式）显示ViewController

0 个答案: