由于 - '''Application tried to present modally an active controller' 未能显示 UIAlertController

Question

我有一个在 UICollectionView 中显示文档的应用程序。每个 UICollectionViewCell 都有一个按钮（与 didSelectItemAt 执行的按钮不同）。这个按钮会弹出一个我使用 UIViewController 创建的自定义弹出窗口。它被呈现 Over Current Context。此弹出窗口显示了一个选项列表，其中一个包括 Delete document。当用户选择后一个选项时，我希望出现 UIAlertController 以确认删除。这是我面临的问题。

这是我的代码：

我得到的错误是：

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Application tried to present modally an active controller .

自定义弹出窗口（UIViewController）

protocol DismissOptionShowDeleteAlert {
    func showDeleteAlert()
}

class MoreOptionsOnPDFViewController: UIViewController, UITableViewDataSource, UITableViewDelegate{

var showDeleteAlertDelegate: DismissOptionShowDeleteAlert!

/ TAP ON ROW
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath){

    ...

     }else if indexPath == [0,4]{ // DELETE DOCUMENT

        DispatchQueue.main.async {
            self.dismiss(animated: true) {
                self.showDeleteAlertDelegate.showDeleteAlert()
            }
        }
    }

    ...

}

UICollectionView:

class CollectionViewFolder: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate ,UICollectionViewDelegateFlowLayout, MoreInfoDocument, MoveFolder, ScanObjectMovedFolder, DismissOptionShowDeleteAlert{

// SHOW DELETE CONFIRMATION ALERT
func showDeleteAlert() {

    Alerts.deleteDocumentConfirm(on: self) {
        // DELETE DOCUMENT FROM SERVER
        print("Delete document ...")
    }
}

}

UIAlertController 结构：

import Foundation
import UIKit

struct Alerts {
private static func showBasicAlert(on vc: UIViewController, with title: String, message: String, action: @escaping (() -> ())){

    let alert =  UIAlertController.init(title: title, message: message, preferredStyle: .alert)
    let okAction = UIAlertAction.init(title: "OK", style: .default) { (UIActionAlert) in

        action()
    }

    let cancelAction = UIAlertAction.init(title: "Cancel", style: .cancel, handler: nil)

    alert.addAction(okAction)
    alert.addAction(cancelAction)
    DispatchQueue.main.async {
        vc.present(vc, animated: true, completion: nil)
    }

}


static func deleteDocumentConfirm(on vc: UIViewController, action: @escaping (() -> ())){
    showBasicAlert(on: vc, with: "Please Confirm Delete", message: "", action: action)
}

}

Answer 1

这正是你的错误所说的。您似乎在呈现视图控制器 vc 而不是 vc

中的 alert

private static func showBasicAlert(on vc: UIViewController, with title: String, message: String, action: @escaping (() -> ())){

    let alert =  UIAlertController.init(title: title, message: message, preferredStyle: .alert)
    let okAction = UIAlertAction.init(title: "OK", style: .default) { (UIActionAlert) in

        action()
    }

    let cancelAction = UIAlertAction.init(title: "Cancel", style: .cancel, handler: nil)

    alert.addAction(okAction)
    alert.addAction(cancelAction)
    DispatchQueue.main.async {
        vc.present(alert, animated: true, completion: nil) // You should be presenting the alert here.
    }

}

Answer 2

您提交的内容有误。您需要显示警报而不是 vc。

将下面的代码替换为您的代码。

struct Alerts {
private static func showBasicAlert(on vc: UIViewController, with title: String, message: String, action: @escaping (() -> ())){

    let alert =  UIAlertController.init(title: title, message: message, preferredStyle: .alert)
    let okAction = UIAlertAction.init(title: "OK", style: .default) { (UIActionAlert) in

        action()
    }

    let cancelAction = UIAlertAction.init(title: "Cancel", style: .cancel, handler: nil)

    alert.addAction(okAction)
    alert.addAction(cancelAction)
    DispatchQueue.main.async {
        vc.present(alert, animated: true, completion: nil)
    }

}

Answer 3

替换下行

vc.present(vc, animated: true, completion: nil)

到

vc.present(alert, animated: true, completion: nil)

由于 - '''Application tried to present modally an active controller' 未能显示 UIAlertController

Failing to show UIAlertController due to - '''Application tried to present modally an active controller'

ios

swift

uialertcontroller